Serena: Semantic Code Tools MCP for Claude Code

Serena by Oraios calls itself “the IDE for your coding agent”. It is an MCP server that gives Claude semantic, symbol-level tools: find a symbol, list references, rename across files, move code, and edit at the level of functions and classes instead of line numbers or text search. It runs on language servers by default or on a JetBrains plugin backend. Serena v2 adds a REPL-based agent interface.

Who it is for

Developers working in large or multi-language codebases where Claude’s grep-and-edit approach becomes slow or error-prone, especially for cross-file refactors.

Install

Serena is managed by uv:

uv tool install -p 3.13 serena-agent
serena init

Then connect it to Claude Code, either automatically:

serena setup claude-code

or manually for all projects:

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

The claude-code context enables a tool subset tuned for Claude Code.

Use cases

• Rename a widely used function and update every reference in one atomic call.
• Find all implementations of an interface before changing its signature.
• Navigate monorepo dependencies by symbol rather than by file path.
• Explore an unfamiliar codebase through symbol overviews instead of reading whole files.

Pros

• Symbol-aware edits are more reliable than text replacement on big refactors.
• Saves tokens by reading only the relevant symbols.
• Free, local, and works with many MCP clients.

Cons and caveats

• Some languages need extra language-server dependencies.
• Adds setup and a background process compared with built-in tools.
• Overlaps with Claude Code’s own code intelligence; measure whether it helps on your repo.

Links

• Repo: oraios/serena
• Docs: oraios.github.io/serena
• Related: context management, GitHub MCP server