setup-serena-mcp

Configures the serena MCP server for the current project by writing (or updating) .mcp.json in the current working directory.

Invocation mechanism

Use uvx --from git+https://github.com/oraios/serena so serena runs in an isolated, auto-fetched environment. This means the user doesn't need to pre-install serena or keep a global install in sync — uvx handles caching and resolution. The only prerequisite is uv on PATH (install via curl -LsSf https://astral.sh/uv/install.sh | sh on Unix).

Why these flags matter

serena runs correctly under Claude Code with both:

• --context claude-code — tunes serena's tool descriptions and reminders for Claude Code. The default context is generic and drops some Claude Code-specific behavior that the serena maintainers ship for this client.
• --project <path> — serena does not auto-detect the project root; without it, serena either refuses to start or operates on the wrong directory.

Config to write

Wrap the launch in sh -c so $PWD expands to the project root at process-launch time rather than hardcoding an absolute path. This keeps .mcp.json portable — it survives the project being moved, renamed, or cloned to a different location, and it works for every teammate who checks out the repo.

The serena entry to add:

"serena": {
  "type": "stdio",
  "command": "sh",
  "args": [
    "-c",
    "uvx --from git+https://github.com/oraios/serena serena start-mcp-server --context claude-code --project \"$PWD\""
  ]
}

Steps

1. Check whether .mcp.json already exists in the current directory.

   • If it exists: read and parse it. If the top-level shape is not {"mcpServers": {...}}, stop and ask the user before overwriting — a different shape likely means the file is managed by a tool you don't want to stomp on.
   • If not: start from {"mcpServers": {}}.

2. Set mcpServers["serena"] to the entry above. Preserve all other mcpServers entries. If a serena entry already exists, overwrite it and note the overwrite to the user.

3. Write the result back to .mcp.json with 2-space indentation and a trailing newline.

4. Tell the user:

   • Whether .mcp.json was created fresh or updated, and whether an existing serena entry was overwritten.
   • To restart their Claude Code session for the change to take effect.
   • That uv must be on PATH for serena to launch. If they don't have it: curl -LsSf https://astral.sh/uv/install.sh | sh.
   • That the first launch will be slow while uvx fetches and caches serena from git; subsequent launches are fast.

Notes

• $PWD is evaluated when Claude Code launches the MCP server process, which inherits the working directory from the terminal. Launch claude from the project root so the path resolves correctly.
• This is a project-level config — it only affects sessions opened in this directory. Commit .mcp.json to the repo if you want teammates to share the setup.
• If there is also a global serena entry in ~/.claude.json (e.g. from claude mcp add --scope user serena ...), the project-level entry takes precedence for sessions opened here, but the two configs can drift. If the user reports unexpected behavior, suggest: claude mcp remove --scope user serena.
• To pin a specific serena version instead of tracking main, change the --from target to git+https://github.com/oraios/serena@<tag-or-sha>.