mcp-code-index 0.3.0

SQLite-backed code index for Claude Code, exposed via MCP

code-index

A SQLite-backed code index for Claude Code, exposed via MCP. Replaces exploratory Read/Grep/Glob calls with targeted retrieval.

What it does

• Parses your repo with tree-sitter (Python, TypeScript/JavaScript, Go, Rust).
• Chunks per symbol; expands identifiers (getUserAuthToken → get user auth token).
• Embeds locally with jina-embeddings-v2-base-code (768d) via sentence-transformers — no API key, no external services.
• Stores symbols, chunks, vectors, and call/import edges in .claude/index.db.
• Serves retrieval over MCP — 8 retrieval tools + 2 admin tools (see below).
• Auto-updates via a Claude Code PostToolUse hook and an optional file watcher.

Tools

Tool	Purpose
init	Build or refresh the project's index. Incremental by default; force=true rebuilds from scratch.
setup_check	Check whether the auto-reindex hook is wired in .claude/settings.json. Returns install instructions if not.
code_search	Hybrid (vector + FTS) search for conceptual queries (e.g., "auth flow", "where do we parse JSON").
symbol_lookup	Exact-name lookup of functions / classes / methods / types. Prefer over code_search for identifiers.
file_outline	Symbols (with signatures) in a file, in source order. Use instead of Read when you only need shape.
get_symbol_body	Full chunk for a symbol_id returned by symbol_lookup or code_search.
callers	Symbols that CALL the given symbol. depth (1-5) expands transitively.
callees	Symbols that the given symbol CALLS. depth (1-5) expands transitively.
dependents	Files that import the given file.
dependencies	Files that the given file imports.

All tools return bounded JSON; large bodies use get_symbol_body rather than inlining whole files.

Requirements

Python with loadable SQLite extension support (required by sqlite-vec). Python 3.13 has this enabled by default. For 3.10–3.12, use either:

• the python.org installer, or
• pyenv: PYTHON_CONFIGURE_OPTS=--enable-loadable-sqlite-extensions pyenv install 3.12.x

Install

In Claude Code (primary)

Preview note: the commands below include uvx --refresh so the latest published version is fetched from PyPI on every Claude Code launch. If you already installed without it, run claude mcp remove code-index first and then re-run the install command. Drop --refresh once you want to pin to a stable version (cuts ~1s off startup).

One command, no API keys:

claude mcp add-json -s user code-index "$(cat <<'JSON'
{
  "type": "stdio",
  "command": "uvx",
  "args": ["--refresh", "--from", "mcp-code-index", "code-index-mcp"]
}
JSON
)"

Drop -s user to register only in the current project (writes to .claude/settings.json instead of ~/.claude.json).

First-run note: the first init downloads jina-embeddings-v2-base-code (~600 MB) into ~/.cache/huggingface. Subsequent runs are fully offline. If your environment blocks Hugging Face downloads, the first index will fail with a network error — pre-warm the cache from a machine that has access.

That's it. Open Claude Code in any repo and ask:

"Build the code index for this repo."

Claude calls the init MCP tool, which writes .claude/index.db for that project. Subsequent prompts can use code_search, symbol_lookup, callers, etc. — see Tools above for the full surface.

Or, with a permanent install (no uvx)

pip install mcp-code-index
claude mcp add -s user code-index -- code-index-mcp

Optional: keep the index live as you edit

Without a hook, the index drifts when files change outside the agent (mv, git checkout, IDE saves) until you call init again. With one, every Edit / Write / MultiEdit Claude performs triggers an incremental reindex of the touched file.

Easiest path: ask Claude. On first use in a new project, ask "is the auto-reindex hook installed?" — Claude calls setup_check, sees the gap, and offers to wire it up.

Manual install — add this block to the project's .claude/settings.json under hooks.PostToolUse:

{
  "matcher": "Edit|Write|MultiEdit",
  "hooks": [
    {
      "type": "command",
      "command": "python -c 'import json,os,subprocess,sys; p=json.load(sys.stdin) if not sys.stdin.isatty() else {}; fp=(p.get(\"tool_input\") or {}).get(\"file_path\"); cwd=p.get(\"cwd\") or os.getcwd(); fp and subprocess.Popen([\"code-index\",\"--root\",cwd,\"reindex\",\"--file\",fp],stdout=subprocess.DEVNULL,stderr=subprocess.DEVNULL,stdin=subprocess.DEVNULL,cwd=cwd,start_new_session=True)'"
    }
  ]
}

In other MCP-compatible agents

The server speaks standard MCP over stdio, so any client that supports MCP servers works (Cursor, Continue, Cody, Zed, etc.). Configure the client to launch uvx --refresh --from mcp-code-index code-index-mcp (or code-index-mcp after pip install mcp-code-index). Once connected, call the init tool from inside the client to bootstrap the index. Drop --refresh when you want to pin to a stable version instead of always pulling latest.

From source (development)

git clone https://github.com/achreftlili/code-index
cd code-index
pip install -e .
code-index init        # CLI alternative to the `init` MCP tool
code-index-mcp         # starts the MCP server on stdio (for manual wiring)

Configuration

Environment variables:

Var	Default	Notes
CODE_INDEX_DB	.claude/index.db	SQLite path.
CODE_INDEX_EMBEDDER	jina	Only jina is supported (local sentence-transformers); the variable exists for future expansion.
CODE_INDEX_EMBED_MODEL	jinaai/jina-embeddings-v2-base-code	HuggingFace model id. Override only if dim-compatible.
CODE_INDEX_EMBED_DIM	768	Must match the model.

Layout

src/code_index/
  db.py           SQLite schema, connection, sqlite-vec loading
  parser.py       Tree-sitter wrapper, symbol + edge extraction
  chunker.py      Per-symbol chunks, identifier expansion
  embedder.py     Local Jina (sentence-transformers) backend
  indexer.py      Pipeline: walk → parse → chunk → embed → write
  retriever.py    Hybrid search (vector + FTS5) with RRF
  watcher.py      File watcher (watchdog)
  mcp_server.py   10 MCP tools (8 retrieval + init/setup_check admin)
  cli.py          init / reindex / watch / stats