Serena 🔌 MCP server Free

What it does

Serena, made by Oraios, is an open-source MCP server that gives a coding agent IDE-style code navigation and editing. Most agents read whole files and edit by searching for text. Serena instead lets the agent work with symbols: it can find a function or class, list what references it, and replace or insert code at the symbol level. On large codebases this means fewer tokens and fewer broken edits. By default, the code analysis comes from language servers, with support for more than 40 languages, including Python, TypeScript, Java, Go, Rust, C#, PHP and Ruby. Serena is licensed under GPL-3.0-or-later.

Tools it gives your agent

• Retrieval: find symbols, get a file's symbol overview, find references, declarations and implementations, and read diagnostics
• Editing: replace a symbol's body, insert code before or after a symbol, rename symbols and delete safely
• Memory: project notes that carry over between sessions, which you can turn off
• Basic tools: regex search, file reading, directory listing and shell commands. These are usually switched off inside Claude Code or Codex, because those agents already have them.

Works with

Serena runs locally. It works with any MCP client, either as a launch command or as an HTTP server you start yourself. Its docs cover Claude Code, Codex, OpenCode, Gemini CLI, Claude Desktop, VS Code, Cursor, JetBrains IDEs with Copilot or Junie, and web clients.

How to connect

Install it with uv, then register it in Claude Code:

uv tool install -p 3.13 serena-agent
serena init
claude mcp add --scope user serena -- serena start-mcp-server --context claude-code --project-from-cwd

The authors warn against installing Serena from MCP or plugin marketplaces, because those listings can carry outdated commands.

Cost and limits

The language-server backend is free. Some languages need extra language-server dependencies installed. An optional Serena JetBrains Plugin uses your JetBrains IDE for analysis instead. It is paid, with a free trial, and adds moves, inlining, type hierarchy and interactive debugging.

Safety notes

Serena edits files directly and can run shell commands through execute_shell_command if that tool is on. Use it in a project under version control and review its diffs. You can switch individual tools off in its YAML config.