Serena

What it does

An MCP server that gives coding agents IDE-style tools: find a symbol, list references, rename across files, replace a function body and read diagnostics, working at the symbol level instead of with line numbers and text search. It uses language servers (free and open source, 40+ languages) by default, or an optional paid JetBrains plugin. It also has a project memory system and a local web dashboard. Serena v2.1.0 was released on 2026-10-19. The Serena application is GPL-3.0-or-later; its SolidLSP component is MIT.

Who it's for

Developers using Claude Code, Codex, Cursor or another MCP client on larger codebases, where cross-file renames and reference lookups by text search get slow or error-prone.

How to set it up

1. Install uv, then install Serena (the project asks you not to install it from MCP or plugin marketplaces, which can carry outdated commands):

   bashCopy

   uv tool install -p 3.13 serena-agent
   serena init

2. Claude Code: let Serena configure it, or add it by hand for all projects:

   bashCopy

   serena setup claude-code
   # or
   claude mcp add --scope user serena -- serena start-mcp-server --context claude-code --project-from-cwd

3. Codex: run serena setup codex. Cursor and other MCP clients: add a server that runs serena start-mcp-server with the ide context, then ask the agent to "Activate the current dir as project using serena":

   jsonCopy

   {
     "mcpServers": {
       "serena": {
         "command": "serena",
         "args": ["start-mcp-server", "--context", "ide"]
       }
     }
   }

4. If it starts too slowly in Claude Code, raise MCP_TIMEOUT (for example export MCP_TIMEOUT=60000). By default Serena opens a web dashboard on localhost when it starts; you can choose whether it opens on launch. Serena's docs also describe optional hooks that remind the agent to use its tools.

Check the official Serena docs for the latest steps.

Example prompts

Activate the current dir as project using serena.

Use serena to find every reference to createInvoice and rename it to createDraftInvoice across the project.

Use serena to give me an overview of the symbols in src/billing/ and where each is used.

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