• 🚀 Serena is a powerful coding agent toolkit capable of turning an LLM into a fully-featured agent that works directly on your codebase. Unlike most other tools, it is not tied to an LLM, framework or an interface, making it easy to use it in a variety of ways.
• 🔧 Serena provides essential semantic code retrieval and editing tools that are akin to an IDE's capabilities, extracting code entities at the symbol level and exploiting relational structure. When combined with an existing coding agent, these tools greatly enhance (token) efficiency.
• 🆓 Serena is free & open-source, enhancing the capabilities of LLMs you already have access to free of charge.

You can think of Serena as an IDE for a coding agent. With it, the agent no longer needs to read entire files, perform grep-like searches or string replacements to find and edit the right code. Instead, it can use code centered tools like find_symbol, find_referencing_symbols and insert_after_symbol.

Most users report that Serena has strong positive effects on the results of their coding agents, even when used within very capable agents like Claude Code. Serena is often described to be a game changer, or an enormous productivity boost.

However, in very small projects or in tasks that involve only one file (tasks which do not require reading/editing only subsets of files), you may not benefit from including Serena. For example, for creating code from scratch, Serena will not provide much value. You also might want to adjust Serena to your needs and workflows using its extensive configuration options.

Several videos and blog posts have been written about Serena by now:

• AI Labs
• Yo Van Eyck
• JeredBlu

• Serena's Design Principles
• Serena with Claude Code (in Japanese)
• Turning Claude Code into a Development Powerhouse

A demonstration of Serena efficiently retrieving and editing code within Claude Code, thereby saving tokens and time. Efficient operations are not only useful for saving costs, but also for generally improving the generated code's quality. This effect may be less pronounced in very small projects, but often becomes of crucial importance in larger ones.

A demonstration of Serena implementing a small feature for itself (a better log GUI) with Claude Desktop. Note how Serena's tools enable Claude to find and edit the right symbols.

Serena is under active development! See the latest updates, upcoming features, and lessons learned to stay up to date.

Serena provides the necessary tools for coding workflows, but an LLM is required to do the actual work, orchestrating tool use.

For example, supercharge the performance of Claude Code with a one-line shell command.

Serena can be integrated with an LLM in several ways:

• by using the model context protocol (MCP).
  Serena provides an MCP server which integrates with
  • Claude Code and Claude Desktop,
  • Terminal-based clients like Codex, Gemini-CLI, Qwen3-Coder, rovodev, OpenHands CLI and others,
  • IDEs like VSCode, Cursor or IntelliJ,
  • Extensions like Cline or Roo Code
  • Local clients like OpenWebUI, Jan, Agno and others
• by using mcpo to connect it to ChatGPT or other clients that don't support MCP but do support tool calling.
• by incorporating Serena's tools into an agent framework of your choice, as illustrated here.
  Serena's tool implementation is decoupled from the framework-specific code and can thus easily be adapted to any agent framework.

Serena's semantic code analysis capabilities build on language servers using the widely implemented language server protocol (LSP). The LSP provides a set of versatile code querying and editing functionalities based on symbolic understanding of the code. Equipped with these capabilities, Serena discovers and edits code just like a seasoned developer making use of an IDE's capabilities would. Serena can efficiently find the right context and do the right thing even in very large and complex projects! So not only is it free and open-source, it frequently achieves better results than existing solutions that charge a premium.

Language servers provide support for a wide range of programming languages. With Serena, we provide

• direct, out-of-the-box support for:

  • Python
  • TypeScript/Javascript
  • PHP (uses Intelephense LSP; set INTELEPHENSE_LICENSE_KEY environment variable for premium features)
  • Go (requires installation of gopls)
  • Rust
  • C#
  • Ruby
  • Swift
  • Java (Note: startup is slow, initial startup especially so. There may be issues with java on macos and linux, we are working on it.)
  • Elixir (Requires NextLS and Elixir install; Windows not supported)
  • Clojure
  • Bash
  • C/C++ (You may experience issues with finding references, we are working on it)

• indirect support (may require some code changes/manual installation) for:

  • Kotlin (untested)
  • Dart (untested)

  These languages are supported by the language server library, but we did not explicitly test whether the support for these languages actually works flawlessly.

Further languages can, in principle, easily be supported by providing a shallow adapter for a new language server implementation.

• Quick Start
  • Running the Serena MCP Server
    • Usage
      • Using uvx
        • Local Installation
      • Using Docker (Experimental)
    • SSE Mode
    • Command-Line Arguments
  • Configuration
  • Project Activation & Indexing
  • Claude Code
  • Codex
  • Other Terminal-Based Clients
  • Claude Desktop
  • MCP Coding Clients (Cline, Roo-Code, Cursor, Windsurf, etc.)
  • Local GUIs and Frameworks
• Detailed Usage and Recommendations
  • Tool Execution
    • Shell Execution and Editing Tools
  • Modes and Contexts
    • Contexts
    • Modes
    • Customization
  • Onboarding and Memories
  • Prepare Your Project
    • Structure Your Codebase
    • Start from a Clean State
    • Logging, Linting, and Automated Tests
  • Prompting Strategies
  • Potential Issues in Code Editing
  • Running Out of Context
  • Combining Serena with Other MCP Servers
  • Serena's Logs: The Dashboard and GUI Tool
  • Troubleshooting
• Comparison with Other Coding Agents
  • Subscription-Based Coding Agents
  • API-Based Coding Agents
  • Other MCP-Based Coding Agents
• Acknowledgements
• Customizing and Extending Serena
• List of Tools

Serena can be used in various ways, below you will find instructions for selected integrations.

• For coding with Claude, we recommend using Serena through Claude Code or Claude Desktop. You can also use Serena in most other terminal-based clients.
• If you want a GUI experience outside an IDE, you can use one of the many local GUIs that support MCP servers. You can also connect Serena to many web clients (including ChatGPT) using mcpo.
• If you want to use Serena integrated in your IDE, see the section on other MCP clients.
• You can use Serena as a library for building your own applications. We try to keep the public API stable, but you should still expect breaking changes and pin Serena to a fixed version if you use it as a dependency.

Serena is managed by uv, so you will need to install it).

You have several options for running the MCP server, which are explained in the subsections below.

The typical usage involves the client (Claude Code, Claude Desktop, etc.) running the MCP server as a subprocess (using stdio communication), so the client needs to be provided with the command to run the MCP server. (Alternatively, you can run the MCP server in SSE mode and tell your client how to connect to it.)

Note that no matter how you run the MCP server, Serena will, by default, start a small web-based dashboard on localhost that will display logs and allow shutting down the MCP server (since many clients fail to clean up processes correctly). This and other settings can be adjusted in the configuration and/or by providing command-line arguments.

uvx can be used to run the latest version of Serena directly from the repository, without an explicit local installation.

uvx --from git+https://github.com/oraios/serena serena start-mcp-server

Explore the CLI to see some of the customization options that serena provides (more info on them below).

1. Clone the repository and change into it.

   git clone https://github.com/oraios/serena
   cd serena

2. Optionally edit the configuration file in your home directory with

   uv run serena config edit

   If you just want the default config, you can skip this part, and a config file will be created when you first run Serena.

3. Run the server with uv:

   uv run serena start-mcp-server

   When running from outside the serena installation directory, be sure to pass it, i.e., use

    uv run --directory /abs/path/to/serena serena start-mcp-server

⚠️ Docker support is currently experimental with several limitations. Please read the Docker documentation for important caveats before using it.

You can run the Serena MCP server directly via docker as follows, assuming that the projects you want to work on are all located in /path/to/your/projects:

docker run --rm -i --network host -v /path/to/your/projects:/workspaces/projects ghcr.io/oraios/serena:latest serena start-mcp-server --transport stdio

Replace /path/to/your/projects with the absolute path to your projects directory. The Docker approach provides:

• Better security isolation for shell command execution
• No need to install language servers and dependencies locally
• Consistent environment across different systems

Alternatively, use docker compose with the compose.yml file provided in the repository.

See the Docker documentation for detailed setup instructions, configuration options, and known limitations.

ℹ️ Note that MCP servers which use stdio as a protocol are somewhat unusual as far as client/server architectures go, as the server necessarily has to be started by the client in order for communication to take place via the server's standard input/output stream. In other words, you do not need to start the server yourself. The client application (e.g. Claude Desktop) takes care of this and therefore needs to be configured with a launch command.

When using instead the SSE mode, which uses HTTP-based communication, you control the server lifecycle yourself, i.e. you start the server and provide the client with the URL to connect to it.

Simply provide start-mcp-server with the --transport sse option and optionally provide the port. For example, to run the Serena MCP server in SSE mode on port 9121 using a local installation, you would run this command from the Serena directory,

uv run serena start-mcp-server --transport sse --port 9121

and then configure your client to connect to http://localhost:9121/sse.

The Serena MCP server supports a wide range of additional command-line options, including the option to run in SSE mode and to adapt Serena to various contexts and modes of operation.

Run with parameter --help to get a list of available options.

Serena is very flexible in terms of configuration. While for most users, the default configurations will work, you can fully adjust it to your needs by editing a few yaml files. You can disable tools, change Serena's instructions (what we denote as the system_prompt), adjust the output of tools that just provide a prompt, and even adjust tool descriptions.

Serena is configured in four places:

1. The serena_config.yml for general settings that apply to all clients and projects. It is located in your user directory under .serena/serena_config.yml. If you do not explicitly create the file, it will be auto-generated when you first run Serena. You can edit it directly or use

   uvx --from git+https://github.com/oraios/serena serena config edit

   (or use the --directory command version).

2. In the arguments passed to the start-mcp-server in your client's config (see below), which will apply to all sessions started by the respective client. In particular, the context parameter should be set appropriately for Serena to be best adjusted to existing tools and capabilities of your client. See for a detailed explanation. You can override all entries from the serena_config.yml through command line arguments.

3. In the .serena/project.yml file within your project. This will hold project-level configuration that is used whenever that project is activated. This file will be autogenerated when you first use Serena on that project, but you can also generate it explicitly with

   uvx --from git+https://github.com/oraios/serena serena project generate-yml

   (or use the --directory command version).

4. Through the context and modes. Explore the modes and contexts section for more details.

After the initial setup, continue with one of the sections below, depending on how you want to use Serena.

If you are mostly working with the same project, you can configure to always activate it at startup by passing --project <path_or_name> to the start-mcp-server command in your client's MCP config. This is especially useful for clients which configure MCP servers on a per-project basis, like Claude Code.

Otherwise, the recommended way is to just ask the LLM to activate a project by providing it an absolute path to, or, in case the project was activated in the past, by its name. The default project name is the directory name.

• "Activate the project /path/to/my_project"
• "Activate the project my_project"

All projects that have been activated will be automatically added to your serena_config.yml, and for each project, the file .serena/project.yml will be generated. You can adjust the latter, e.g., by changing the name (which you refer to during the activation) or other options. Make sure to not have two different projects with the same name.

ℹ️ For larger projects, we recommend that you index your project to accelerate Serena's tools; otherwise the first tool application may be very slow. To do so, run this from the project directory (or pass the path to the project as an argument):

uvx --from git+https://github.com/oraios/serena serena project index

(or use the --directory command version).

Serena is a great way to make Claude Code both cheaper and more powerful!

From your project directory, add serena with a command like this,

claude mcp add serena -- <serena-mcp-server> --context ide-assistant --project $(pwd)

where <serena-mcp-server> is your way of running the Serena MCP server. For example, when using uvx, you would run

claude mcp add serena -- uvx --from git+https://github.com/oraios/serena serena start-mcp-server --context ide-assistant --project $(pwd)

ℹ️ Serena comes with an instruction text, and Claude needs to read it to properly use Serena's tools. As of version v1.0.52, claude code reads the instructions of the MCP server, so this is handled automatically. If you are using an older version, or if Claude fails to read the instructions, you can ask it explicitly to "read Serena's initial instructions" or run /mcp__serena__initial_instructions to load the instruction text. If you want to make use of that, you will have to enable the corresponding tool explicitly by adding initial_instructions to the included_optional_tools in your config. Note that you may have to make Claude read the instructions when you start a new conversation and after any compacting operation to ensure Claude remains properly configured to use Serena's tools.

Serena works with OpenAI's Codex CLI out of the box, but you have to use the codex context for it to work properly. (The technical reason is that Codex doesn't fully support the MCP specifications, so some massaging of tools is required.).

Unlike Claude Code, in Codex you add an MCP server globally and not per project. Add the following to ~/.codex/config.toml (create the file if it does not exist):

[mcp_servers.serena]
command = "uvx"
args = ["--from", "git+https://github.com/oraios/serena", "serena", "start-mcp-server", "--context", "codex"]

After codex has started, you need to activate the project, which you can do by saying:

"Activate the current dir as project using serena"

If you don't activate the project, you will not be able to use Serena's tools!

That's it! Have a look at ~/.codex/log/codex-tui.log to see if any errors occurred.

The Serena dashboard will run if you have not disabled it in the configuration, but due to Codex's sandboxing the webbrowser may not open automatically. You can open it manually by going to http://localhost:24282/dashboard/index.html (or a higher port, if that was already taken).

Codex will often show the tools as failed even though they are successfully executed. This is not a problem, seems to be a bug in Codex. Despite the error message, everything works as expected.

There are many terminal-based coding assistants that support MCP servers, such as Codex, Gemini-CLI, Qwen3-Coder, rovodev, the OpenHands CLI and opencode.

They generally benefit from the symbolic tools provided by Serena. You might want to customize some aspects of Serena by writing your own context, modes or prompts to adjust it to your workflow, to other MCP servers you are using, and to the client's internal capabilities.

For Claude Desktop (available for Windows and macOS), go to File / Settings / Developer / MCP Servers / Edit Config, which will let you open the JSON file claude_desktop_config.json. Add the serena MCP server configuration, using a run command depending on your setup.

• local installation:

  {
      "mcpServers": {
          "serena": {
              "command": "/abs/path/to/uv",
              "args": ["run", "--directory", "/abs/path/to/serena", "serena", "start-mcp-server"]
          }
      }
  }

• uvx:

  {
      "mcpServers": {
          "serena": {
              "command": "/abs/path/to/uvx",
              "args": ["--from", "git+https://github.com/oraios/serena", "serena", "start-mcp-server"]
          }
      }
  }

• docker:

   {
       "mcpServers": {
           "serena": {
               "command": "docker",
               "args": ["run", "--rm", "-i", "--network", "host", "-v", "/path/to/your/projects:/workspaces/projects", "ghcr.io/oraios/serena:latest", "serena", "start-mcp-server", "--transport", "stdio"]
           }
       }
   }

If you are using paths containing backslashes for paths on Windows (note that you can also just use forward slashes), be sure to escape them correctly (\\).

That's it! Save the config and then restart Claude Desktop. You are ready for activating your first project.

ℹ️ You can further customize the run command using additional arguments (see above).

Note: on Windows and macOS there are official Claude Desktop applications by Anthropic, for Linux there is an open-source community version.

⚠️ Be sure to fully quit the Claude Desktop application, as closing Claude will just minimize it to the system tray – at least on Windows.

⚠️ Some clients may leave behind zombie processes. You will have to find and terminate them manually then. With Serena, you can activate the dashboard to prevent unnoted processes and also use the dashboard for shutting down Serena.

After restarting, you should see Serena's tools in your chat interface (notice the small hammer icon).

For more information on MCP servers with Claude Desktop, see the official quick start guide.

Being an MCP Server, Serena can be included in any MCP Client. The same configuration as above, perhaps with small client-specific modifications, should work. Most of the popular existing coding assistants (IDE extensions or VSCode-like IDEs) support connections to MCP Servers. It is recommended to use the ide-assistant context for these integrations by adding "--context", "ide-assistant" to the args in your MCP client's configuration. Including Serena generally boosts their performance by providing them tools for symbolic operations.

In this case, the billing for the usage continues to be controlled by the client of your choice (unlike with the Claude Desktop client). But you may still want to use Serena through such an approach, e.g., for one of the following reasons:

1. You are already using a coding assistant (say Cline or Cursor) and just want to make it more powerful.
2. You are on Linux and don't want to use the community-created Claude Desktop.
3. You want tighter integration of Serena into your IDE and don't mind paying for that.

Over the last months, several technologies have emerged that allow you to run a powerful local GUI and connect it to an MCP server. They will work with Serena out of the box. Some of the leading open source GUI technologies offering this are Jan, OpenHands, OpenWebUI and Agno. They allow combining Serena with almost any LLM (including locally running ones) and offer various other integrations.

Serena combines tools for semantic code retrieval with editing capabilities and shell execution. Serena's behavior can be further customized through Modes and Contexts. Find the complete list of tools below.

The use of all tools is generally recommended, as this allows Serena to provide the most value: Only by executing shell commands (in particular, tests) can Serena identify and correct mistakes autonomously.

However, it should be noted that the execute_shell_command tool allows for arbitrary code execution. When using Serena as an MCP Server, clients will typically ask the user for permission before executing a tool, so as long as the user inspects execution parameters beforehand, this should not be a problem. However, if you have concerns, you can choose to disable certain commands in your project's .yml configuration file. If you only want to use Serena purely for analyzing code and suggesting implementations without modifying the codebase, you can enable read-only mode by setting read_only: true in your project configuration file. This will automatically disable all editing tools and prevent any modifications to your codebase while still allowing all analysis and exploration capabilities.

In general, be sure to back up your work and use a version control system in order to avoid losing any work.

Serena's behavior and toolset can be adjusted using contexts and modes. These allow for a high degree of customization to best suit your workflow and the environment Serena is operating in.

A context defines the general environment in which Serena is operating. It influences the initial system prompt and the set of available tools. A context is set at startup when launching Serena (e.g., via CLI options for an MCP server or in the agent script) and cannot be changed during an active session.

Serena comes with pre-defined contexts:

• desktop-app: Tailored for use with desktop applications like Claude Desktop. This is the default.
• agent: Designed for scenarios where Serena acts as a more autonomous agent, for example, when used with Agno.
• ide-assistant: Optimized for integration into IDEs like VSCode, Cursor, or Cline, focusing on in-editor coding assistance. Choose the context that best matches the type of integration you are using.

When launching Serena, specify the context using --context <context-name>.
Note that for cases where parameter lists are specified (e.g. Claude Desktop), you must add two parameters to the list.

Modes further refine Serena's behavior for specific types of tasks or interaction styles. Multiple modes can be active simultaneously, allowing you to combine their effects. Modes influence the system prompt and can also alter the set of available tools by excluding certain ones.

Examples of built-in modes include:

• planning: Focuses Serena on planning and analysis tasks.
• editing: Optimizes Serena for direct code modification tasks.
• interactive: Suitable for a conversational, back-and-forth interaction style.
• one-shot: Configures Serena for tasks that should be completed in a single response, often used with planning for generating reports or initial plans.
• no-onboarding: Skips the initial onboarding process if it's not needed for a particular session.
• onboarding: (Usually triggered automatically) Focuses on the project onboarding process.

Modes can be set at startup (similar to contexts) but can also be switched dynamically during a session. You can instruct the LLM to use the switch_modes tool to activate a different set of modes (e.g., "switch to planning and one-shot modes").

When launching Serena, specify modes using --mode <mode-name>; multiple modes can be specified, e.g. --mode planning --mode no-onboarding.

⚠️ Mode Compatibility: While you can combine modes, some may be semantically incompatible (e.g., interactive and one-shot). Serena currently does not prevent incompatible combinations; it is up to the user to choose sensible mode configurations.

You can create your own contexts and modes to precisely tailor Serena to your needs in two ways:

• You can use Serena's CLI to manage modes and contexts. Check out

  uvx --from git+https://github.com/oraios/serena serena mode --help

  and

  uvx --from git+https://github.com/oraios/serena serena context --help

  NOTE: Custom contexts/modes are simply YAML files in <home>/.serena, they are automatically registered and available for use by their name (filename without the .yml extension). If you don't want to use Serena's CLI, you can create and manage them in any way you see fit.

• Using external YAML files: When starting Serena, you can also provide an absolute path to a custom .yml file for a context or mode.

This customization allows for deep integration and adaptation of Serena to specific project requirements or personal preferences.

By default, Serena will perform an onboarding process when it is started for the first time for a project. The goal of the onboarding is for Serena to get familiar with the project and to store memories, which it can then draw upon in future interactions. If an LLM should fail to complete the onboarding and does not actually write the respective memories to disk, you may need to ask it to do so explicitly.

The onboarding will usually read a lot of content from the project, thus filling up the context. It can therefore be advisable to switch to another conversation once the onboarding is complete. After the onboarding, we recommend that you have a quick look at the memories and, if necessary, edit them or add additional ones.

Memories are files stored in .serena/memories/ in the project directory, which the agent can choose to read in subsequent interactions. Feel free to read and adjust them as needed; you can also add new ones manually. Every file in the .serena/memories/ directory is a memory file. Whenever Serena starts working on a project, the list of memories is provided, and the agent can decide to read them. We found that memories can significantly improve the user experience with Serena.

Serena uses the code structure for finding, reading and editing code. This means that it will work well with well-structured code but may perform poorly on fully unstructured one (like a "God class" with enormous, non-modular functions).
Furthermore, for languages that are not statically typed, type annotations are highly beneficial.

It is best to start a code generation task from a clean git state. Not only will this make it easier for you to inspect the changes, but also the model itself will have a chance of seeing what it has changed by calling git diff and thereby correct itself or continue working in a followup conversation if needed.

⚠️ Important: since Serena will write to files using the system-native line endings and it might want to look at the git diff, it is important to set git config core.autocrlf to true on Windows. With git config core.autocrlf set to false on Windows, you may end up with huge diffs only due to line endings. It is generally a good idea to globally enable this git setting on Windows:

git config --global core.autocrlf true

Serena can successfully complete tasks in an agent loop, where it iteratively acquires information, performs actions, and reflects on the results. However, Serena cannot use a debugger; it must rely on the results of program executions, linting results, and test results to assess the correctness of its actions. Therefore, software that is designed to meaningful interpretable outputs (e.g. log messages) and that has a good test coverage is much easier to work with for Serena.

We generally recommend to start an editing task from a state where all linting checks and tests pass.

We found that it is often a good idea to spend some time conceptualizing and planning a task before actually implementing it, especially for non-trivial task. This helps both in achieving better results and in increasing the feeling of control and staying in the loop. You can make a detailed plan in one session, where Serena may read a lot of your code to build up the context, and then continue with the implementation in another (potentially after creating suitable memories).

In our experience, LLMs are bad at counting, i.e. they have problems inserting blocks of code in the right place. Most editing operations can be performed at the symbolic level, allowing this problem is overcome. However, sometimes, line-level insertions are useful.

Serena is instructed to double-check the line numbers and any code blocks that it will edit, but you may find it useful to explicitly tell it how to edit code if you run into problems.
We are working on making Serena's editing capabilities more robust.

For long and complicated tasks, or tasks where Serena has read a lot of content, you may come close to the limits of context tokens. In that case, it is often a good idea to continue in a new conversation. Serena has a dedicated tool to create a summary of the current state of the progress and all relevant info for continuing it. You can request to create this summary and write it to a memory. Then, in a new conversation, you can just ask Serena to read the memory and continue with the task. In our experience, this worked really well. On the up-side, since in a single session there is no summarization involved, Serena does not usually get lost (unlike some other agents that summarize under the hood), and it is also instructed to occasionally check whether it's on the right track.

Moreover, Serena is instructed to be frugal with context (e.g., to not read bodies of code symbols unnecessarily), but we found that Claude is not always very good in being frugal (Gemini seemed better at it). You can explicitly instruct it to not read the bodies if you know that it's not needed.

When using Serena through an MCP Client, you can use it together with other MCP servers. However, beware of tool name collisions! See info on that above.

Currently, there is a collision with the popular Filesystem MCP Server. Since Serena also provides filesystem operations, there is likely no need to ever enable these two simultaneously.

Serena provides two convenient ways of accessing the logs of the current session:

• via the web-based dashboard (enabled by default)

  This is supported on all platforms. By default, it will be accessible at http://localhost:24282/dashboard/index.html, but a higher port may be used if the default port is unavailable/multiple instances are running.

• via the GUI tool (disabled by default)

  This is mainly supported on Windows, but it may also work on Linux; macOS is unsupported.

Both can be enabled, configured or disabled in Serena's configuration file (serena_config.yml, see above). If enabled, they will automatically be opened as soon as the Serena agent/MCP server is started. The web dashboard will display usage statistics of Serena's tools if you set record_tool_usage_stats: True in your config.

In addition to viewing logs, both tools allow to shut down the Serena agent. This function is provided, because clients like Claude Desktop may fail to terminate the MCP server subprocess when they themselves are closed.

Support for MCP Servers in Claude Desktop and the various MCP Server SDKs are relatively new developments and may display instabilities.

The working configuration of an MCP server may vary from platform to platform and from client to client. We recommend always using absolute paths, as relative paths may be sources of errors. The language server is running in a separate sub-process and is called with asyncio – sometimes a client may make it crash. If you have Serena's log window enabled, and it disappears, you'll know what happened.

Some clients may not properly terminate MCP servers, look out for hanging python processes and terminate them manually, if needed.

To our knowledge, Serena is the first fully-featured coding agent where the entire functionality is available through an MCP server, thus not requiring API keys or subscriptions.

Many prominent subscription-based coding agents are parts of IDEs like Windsurf, Cursor and VSCode. Serena's functionality is similar to Cursor's Agent, Windsurf's Cascade or VSCode's agent mode.

Serena has the advantage of not requiring a subscription. A potential disadvantage is that it is not directly integrated into an IDE, so the inspection of newly written code is not as seamless.

More technical differences are:

• Serena is not bound to a specific IDE or CLI. Serena's MCP server can be used with any MCP client (including some IDEs), and the Agno-based agent provides additional ways of applying its functionality.
• Serena is not bound to a specific large language model or API.
• Serena navigates and edits code using a language server, so it has a symbolic understanding of the code. IDE-based tools often use a RAG-based or purely text-based approach, which is often less powerful, especially for large codebases.
• Serena is open-source and has a small codebase, so it can be easily extended and modified.

An alternative to subscription-based agents are API-based agents like Claude Code, Cline, Aider, Roo Code and others, where the usage costs map directly to the API costs of the underlying LLM. Some of them (like Cline) can even be included in IDEs as an extension. They are often very powerful and their main downside are the (potentially very high) API costs.

Serena itself can be used as an API-based agent (see the section on Agno above). We have not yet written a CLI tool or a dedicated IDE extension for Serena (and there is probably no need for the latter, as Serena can already be used with any IDE that supports MCP servers). If there is demand for a Serena as a CLI tool like Claude Code, we will consider writing one.

The main difference between Serena and other API-based agents is that Serena can also be used as an MCP server, thus not requiring an API key and bypassing the API costs. This is a unique feature of Serena.

There are other MCP servers designed for coding, like DesktopCommander and codemcp. However, to the best of our knowledge, none of them provide semantic code retrieval and editing tools; they rely purely on text-based analysis. It is the integration of language servers and the MCP that makes Serena unique and so powerful for challenging coding tasks, especially in the context of larger codebases.

We built Serena on top of multiple existing open-source technologies, the most important ones being:

1. multilspy. A library which wraps language server implementations and adapts them for interaction via Python and which provided the basis for our library Solid-LSP (src/solidlsp). Solid-LSP provides pure synchronous LSP calls and extends the original library with the symbolic logic that Serena required.
2. Python MCP SDK
3. Agno and the associated agent-ui, which we use to allow Serena to work with any model, beyond the ones supporting the MCP.
4. All the language servers that we use through Solid-LSP.

Without these projects, Serena would not have been possible (or would have been significantly more difficult to build).

It is straightforward to extend Serena's AI functionality with your own ideas. Simply implement a new tool by subclassing serena.agent.Tool and implement the apply method with a signature that matches the tool's requirements. Once implemented, SerenaAgent will automatically have access to the new tool.

It is also relatively straightforward to add support for a new programming language.

We look forward to seeing what the community will come up with! For details on contributing, see contributing guidelines.

Here is the list of Serena's default tools with a short description (output of uv run serena tools list):

• activate_project: Activates a project by name.
• check_onboarding_performed: Checks whether project onboarding was already performed.
• create_text_file: Creates/overwrites a file in the project directory.
• delete_memory: Deletes a memory from Serena's project-specific memory store.
• execute_shell_command: Executes a shell command.
• find_file: Finds files in the given relative paths
• find_referencing_symbols: Finds symbols that reference the symbol at the given location (optionally filtered by type).
• find_symbol: Performs a global (or local) search for symbols with/containing a given name/substring (optionally filtered by type).
• get_symbols_overview: Gets an overview of the top-level symbols defined in a given file.
• insert_after_symbol: Inserts content after the end of the definition of a given symbol.
• insert_before_symbol: Inserts content before the beginning of the definition of a given symbol.
• list_dir: Lists files and directories in the given directory (optionally with recursion).
• list_memories: Lists memories in Serena's project-specific memory store.
• onboarding: Performs onboarding (identifying the project structure and essential tasks, e.g. for testing or building).
• prepare_for_new_conversation: Provides instructions for preparing for a new conversation (in order to continue with the necessary context).
• read_file: Reads a file within the project directory.
• read_memory: Reads the memory with the given name from Serena's project-specific memory store.
• replace_regex: Replaces content in a file by using regular expressions.
• replace_symbol_body: Replaces the full definition of a symbol.
• search_for_pattern: Performs a search for a pattern in the project.
• think_about_collected_information: Thinking tool for pondering the completeness of collected information.
• think_about_task_adherence: Thinking tool for determining whether the agent is still on track with the current task.
• think_about_whether_you_are_done: Thinking tool for determining whether the task is truly completed.
• write_memory: Writes a named memory (for future reference) to Serena's project-specific memory store.

There are several tools that are disabled by default, and have to be enabled explicitly, e.g., through the context or modes. Note that several of our default contexts do enable some of these tools. For example, the desktop-app context enables the execute_shell_command tool.

The full list of optional tools is (output of uv run serena tools list --only-optional):

• delete_lines: Deletes a range of lines within a file.
• get_current_config: Prints the current configuration of the agent, including the active and available projects, tools, contexts, and modes.
• initial_instructions: Gets the initial instructions for the current project. Should only be used in settings where the system prompt cannot be set, e.g. in clients you have no control over, like Claude Desktop.
• insert_at_line: Inserts content at a given line in a file.
• jet_brains_find_referencing_symbols: Finds symbols that reference the given symbol
• jet_brains_find_symbol: Performs a global (or local) search for symbols with/containing a given name/substring (optionally filtered by type).
• jet_brains_get_symbols_overview: Retrieves an overview of the top-level symbols within a specified file
• remove_project: Removes a project from the Serena configuration.
• replace_lines: Replaces a range of lines within a file with new content.
• restart_language_server: Restarts the language server, may be necessary when edits not through Serena happen.
• summarize_changes: Provides instructions for summarizing the changes made to the codebase.
• switch_modes: Activates modes by providing a list of their names