Codeix — Claude Code MCP server: semantic code search
Builds a .codeindex and answers agent queries about symbols, callers and comments. Useful when your agent burns tokens hunting for a function.
claude mcp add codeix -- npx -y codeixWhat Codeix does
Codeix is an MCP server that gives coding agents a pre-built map of a codebase. You run codeix build to parse sources into a .codeindex directory, then start the server with plain codeix and it watches for changes. Under the hood: Rust, tree-sitter and in-memory SQLite FTS5. Builds take seconds, queries return in milliseconds.
The index is plain JSONL — index.json, files.jsonl, symbols.jsonl, texts.jsonl. Commit it with your code, ship it inside an npm, PyPI or crates.io package, or read it with jq. The server discovers dependency indexes on its own and mounts them, so one query can span your code and your libraries.
Seven tools are exposed: explore, search, get_file_symbols, get_children, get_callers, get_callees, flush_index. With --scope text the search hits only comments, docstrings and string literals — handy for tracking down a TODO or the exact wording of an error message. Language grammars are feature-gated at compile time and Python, Rust, JavaScript, TypeScript, Go, Java, C, C++, Ruby, C# and Markdown are on by default. HTML, Vue, Svelte and Astro files get their embedded <script> blocks extracted, and line numbers still point at the original file. Launch codeix from any directory and it walks downward, treating every folder with .git/ as its own project — monorepos and sibling repos work without config.
What it helps with
- locate a function definition and its signature in one call
- trace every caller of a method, including ones in dependencies
- search comments and docstrings without matching code
- hand a ready-made index to a teammate or a CI runner
- map the structure of a monorepo with several packages
Example prompts for the agent
- Use codeix to find every place that calls
Config.__init__ - List the symbols in
src/main.pywith their line ranges - Search comments and string literals for
TODOacross the project
How to install Codeix
Platform CLI
claude mcp add codeix -- npx -y codeixPlatform CLI
codex mcp add codeix -- npx -y codeixConfig file
{
"mcpServers": {
"codeix": {
"command": "npx",
"args": [
"-y",
"codeix"
]
}
}
}Config file
{
"servers": {
"codeix": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"codeix"
]
}
}
}Platform CLI
gemini mcp add codeix npx -y codeixStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Codeix
How do I install Codeix in Claude Code?
Run claude mcp add codeix -- npx -y codeix. Nothing else to install — npx fetches the package.
What does Codeix do?
It parses your sources into a .codeindex and answers agent questions about symbols, files, callers and comments. The agent gets a map instead of re-reading files.
Does it need configuration after launch?
No. The server starts querying right away and finds projects by itself — every directory containing .git/ becomes a separate project with its own .codeindex.
