A powerful toolkit for coding, providing semantic retrieval and editing capabilities.
io.github.oraios/serena MCP Server
The io.github.oraios/serena MCP server is described as a coding toolkit that offers semantic retrieval and editing capabilities. It is positioned for agent-driven coding workflows, with topics spanning language-server and IDE integration.
Serena provides essential semantic code retrieval, editing, refactoring and debugging tools that are akin to an IDE's capabilities,
operating at the symbol level and exploiting relational structure.
It integrates with any client/LLM via the model context protocol (MCP).
Serena's agent-first tool design involves robust high-level abstractions, distinguishing it from
approaches that rely on low-level concepts like line numbers or primitive search patterns.
Practically, this means that your agent operates faster, more efficiently and more reliably, especially in larger and
more complex codebases.
IMPORTANT
Do not install Serena via an MCP or plugin marketplace! They contain outdated and suboptimal installation commands.
Instead, follow our Quick Start instructions.
While it is humans who download and set up Serena, our end users are essentially AI agents.
As the ones actually applying Serena's tools, they are in the best position to evaluate Serena.
We crafted an unbiased evaluation prompt that leads the agent to perform ~20 routine coding tasks,
representative of everyday development work,
in order to estimate the value added by Serena's tools when used alongside its own built-ins.
Here's a one-sentence summary of what the agents had to say:
Opus 4.6 (high) in Claude Code on a large Python codebase:
"Serena's IDE-backed semantic tools are the single most impactful addition to my toolkit – cross-file renames, moves, and reference lookups that
would cost me 8–12 careful, error-prone steps collapse into one atomic call, and I would absolutely ask any developer I work with to set them up."
GPT 5.4 (high) in Codex CLI on a Java codebase:
"As a coding AI agent, I would ask my owner to add Serena because it gives me the missing IDE-level understanding of symbols, references, and
refactorings, turning fragile text surgery into calmer, faster, more confident code changes where semantics matter."
GPT 5.4 (medium) in Copilot CLI on a large, multi-language monorepo:
"As a coding agent, I’d absolutely ask my owner to add Serena because it makes me noticeably sharper and calmer on
real code – especially symbol-aware navigation, cross-file refactors, and monorepo dependency jumps – while I still lean
on built-ins for tiny text edits and non-code work."
Different agents in different settings independently converge on the same verdict.
Give your agent the tools it has been asking for and add Serena MCP to your client!
See our documentation for the full methodology and much more detailed evaluation results, or run your own evaluation on a project of your choice.
How Serena Works
Serena provides the necessary tools for coding workflows,
but an LLM is required to do the actual work, orchestrating tool use.
Serena can extend the functionality of your existing AI client via the model context protocol (MCP).
Most modern AI chat clients directly support MCP, including
terminal-based clients like Claude Code, Codex, OpenCode, or Gemini-CLI,
IDEs and IDE assistant plugins for VSCode, Cursor and JetBrains IDEs (Copilot, Junie, JetBrains AI Assistant, etc.),
desktop and web clients like Claude Desktop, Codex App, or OpenWebUI.
To connect the Serena MCP server to your client, you either
provide the client with a launch command that allows it to start the MCP server, or
start the Serena MCP server yourself in HTTP mode and provide the client with the URL.
See the Quick Start section below for information on how to get started.
Programming Language Support & Semantic Analysis Capabilities
Serena provides a set of versatile code querying and editing functionalities
based on symbolic understanding of the code.
Equipped with these capabilities, your agent 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!
There are two alternative technologies powering these capabilities:
Language servers implementing the language server protocol (LSP) — the free/open-source alternative
which is used by default.
The Serena JetBrains Plugin, which leverages the powerful code analysis and editing
capabilities of your JetBrains IDE (paid plugin; free trial available).
You can choose either of these backends depending on your preferences and requirements.
Language Servers
Serena incorporates a powerful abstraction layer for the integration of language servers that implement the language server protocol (LSP).
The underlying language servers are typically open-source projects or at least freely available for use.
When using Serena's language server backend, we provide support for over 40 programming languages, including
Ada / SPARK, AL, Angular, Ansible, Bash, BSL, C#, C/C++, Clojure, Crystal, CUE, Dart, Deno, Elixir, Elm, Erlang, Fortran, F#, GDScript, Gleam, GLSL, Go, Groovy, Haskell, Haxe, HLSL, HTML, Java, JavaScript, JSON, Julia, Kotlin, LaTeX, Lean 4, Lua, Luau, Markdown, MATLAB, mSL, Nextflow, Nix, OCaml, Pascal, Perl, PHP, PowerShell, Python, QML, R, Rego, Ruby, Rust, Scala, SCSS / Sass / CSS, Solidity, Svelte, Swift, SystemVerilog, Terraform, TOML, TypeScript, Vue, WGSL, Wolfram Language, YAML, and Zig.
The Serena JetBrains Plugin
The paid Serena JetBrains Plugin (free trial available)
leverages the powerful code analysis capabilities of your JetBrains IDE.
The plugin naturally supports all programming languages and frameworks that are supported by JetBrains IDEs,
including IntelliJ IDEA, PyCharm, Android Studio, WebStorm, PhpStorm, RubyMine, GoLand, and potentially others (Rider and CLion are unsupported though).
See our documentation page for further details and instructions on how to apply the plugin.
Features
Serena provides a wide range of tools for efficient code retrieval, editing and refactoring, as well as
a memory system for long-lived agent workflows.
Given its large scope, Serena adapts to your needs by offering a multi-layered configuration system.
Details
Retrieval
Serena's retrieval tools allow agents to explore codebases at the symbol level, understanding structure and relationships
without reading entire files.
Capability
Language Servers
JetBrains Plugin
find symbol
yes
yes
symbol overview (file outline)
yes
yes
find referencing symbols
yes
yes
search in project dependencies
--
yes
type hierarchy
--
yes
find declaration
yes*
yes
find implementations
yes**
yes
query external projects
yes
yes
diagnostics/inspections
yes
yes
*: Will generally not work for declarations in external dependencies.
**: Only available for some languages, limited by the language server functionality.
Refactoring
Without precise refactoring tools, agents are forced to resort to unreliable and expensive search and replace operations.
Capability
Language Servers
JetBrains Plugin
rename
yes (only symbols)
yes (symbols, files, directories)
move (symbol, file, directory)
--
yes
inline
--
yes
propagate deletions (remove unused code)
--
yes
Symbolic Editing
Serena's symbolic editing tools are less error-prone and much more token-efficient than typical alternatives.
Capability
Language Servers
JetBrains Plugin
replace symbol body
yes
yes
insert after symbol
yes
yes
insert before symbol
yes
yes
safe delete
yes
yes
Interactive Debugging
Exclusive to the JetBrains plugin, Serena supports a highly general debugging tool,
which allows an agent to set breakpoints, inspect variables, evaluate expressions and control execution flow
via a persistent REPL-style interface.
Basic Features
Beyond its semantic capabilities, Serena includes a set of basic utilities for completeness.
When Serena is used inside an agentic harness such as Claude Code or Codex, these tools are typically disabled by default,
since the surrounding harness already provides overlapping file, search, and shell capabilities.
search_for_pattern – flexible regex search across the codebase
replace_content – agent-optimised regex-based and literal text replacement
list_dir / find_file – directory listing and file search
read_file – read files or file chunks
execute_shell_command – run shell commands (e.g. builds, tests, linters)
Memory Management
A memory system is elemental to long-lived agent workflows, especially when knowledge is to be shared across
sessions, users and projects.
Despite its simplicity, we received positive feedback from many users who tend to combine Serena's memory management system with their
agent's internal system (e.g., AGENTS.md files).
It can easily be disabled if you prefer to use something else.
Configurability
Active tools, tool descriptions, prompts, language backend details and many other aspects of Serena
can be flexibly configured on a per-case basis by simply adjusting a few lines of YAML.
To achieve this, Serena offers multiple levels of (composable) configuration:
global configuration
MCP launch command (CLI) configuration
per-project configuration (with local overrides)
execution context-specific configuration (e.g. for particular clients)
Prerequisites. Serena is managed by uv, and installing uv is the only required prerequisite.
NOTE
When using the language server backend, some additional dependencies may need to be installed to support certain languages;
see the Language Support page for details.
Install Serena. Serena is installed via uv as follows:
bash
uv tool install -p 3.13 serena-agent
After successful installation, the command serena should be available in your shell.
Initialise Serena. To initialise Serena and verify that your setup works correctly, simply run:
bash
serena init
By default, this will set up Serena to use the language server backend. To use the JetBrains backend instead, add the parameters -b JetBrains
(see the JetBrains Plugin documentation page for additional usage details).
Either way, you should receive a success message indicating that Serena has been initialised successfully.
Configuring Your Client. To connect Serena to your preferred MCP client, you typically need to configure a launch command in your client.
Follow the link for specific instructions on how to set up Serena for Claude Code, Codex, Claude Desktop, MCP-enabled IDEs and other clients (such as local and web-based GUIs).
TIP
While getting started quickly is easy, Serena is a powerful toolkit with many configuration options.
We highly recommend reading through the user guide to get the most out of Serena.
Please refer to the user guide for detailed instructions on how to use Serena effectively.
Acknowledgements
A significant part of Serena, especially support for various languages, was contributed by the open source community.
We are very grateful for the many contributors who made this possible and who played an important role in making Serena
what it is today.
License
Serena is licensed per component: SolidLSP (src/solidlsp) under the MIT License,
the Serena application (everything else) under GPL-3.0-or-later.
Distributions combining both are as a whole subject to the GPL.
