Code-Graph-MCP: Open Source MCP Server Cuts Token Usage 40-60%

code-graph-mcp is an open source MCP server that indexes codebases into an AST knowledge graph to reduce Claude Code token usage. Instead of Claude making multiple grep/read/glob calls to understand code structure, it queries the graph for structured answers in single calls.

How It Works

The tool parses code with Tree-sitter, extracts symbols (functions, classes, types, interfaces) and their relationships (calls, imports, inheritance, exports, HTTP route bindings), then stores everything in SQLite with FTS5 full-text search and sqlite-vec for vector similarity. It supports 10 languages: TypeScript, JavaScript, Go, Python, Rust, Java, C, C++, HTML, and CSS.

Key Tools

project_map — Full architecture overview in one call (modules, dependencies, hot functions, entry points)
semantic_code_search — Hybrid search combining BM25 + vector similarity with RRF fusion
get_call_graph — Trace callers/callees with recursive CTEs
impact_analysis — See everything that depends on a function before changing it
trace_http_chain — Trace HTTP routes from handler to DB call (supports Express, Flask/FastAPI, Go)
module_overview, dependency_graph, find_similar_code, get_ast_node — Additional toolkit functions

Efficiency Results

On a 33-file Rust project:

Understanding project architecture: Reduced from 5-8 tool calls to 1 call
Tracing a 2-level call chain: Reduced from 8-15 calls to 1 call
Pre-change impact analysis: Reduced from 10-20+ calls to 1 call
Finding function by concept: Reduced from 3-5 calls to 1 call

Overall: ~80% fewer tool calls per navigation task, ~95% less source code dumped into context, and 40-60% total session token savings.

Technical Details

Incremental indexing uses BLAKE3 Merkle tree to track content hashes — only changed files get re-parsed. Unchanged directory subtrees skip entirely via mtime cache. When a function signature changes, dirty propagation regenerates context for all downstream callers automatically.

The tool has zero external dependencies — it's a single 19MB binary with embedded SQLite and bundled sqlite-vec. No Docker, cloud API, or database server required. Optional local embeddings use a Candle-based embedding model, feature-gated so you can build without it if vector search isn't needed.

Installation

Works with Claude Code, Cursor, Windsurf, or any MCP client.

Claude Code plugin (recommended):

/plugin marketplace add sdsrss/code-graph-mcp
/plugin install code-graph-mcp

This includes the MCP server plus slash commands (/understand, /trace, /impact), auto-indexing hooks (re-indexes on every file edit), StatusLine health display, and automatic updates.

For any MCP client:

npx -y @sdsrs/code-graph

Or add to your MCP config:

{
  "mcpServers": {
    "code-graph": {
      "command": "npx",
      "args": ["-y", "@sdsrs/code-graph"]
    }
  }
}

When Not to Use It

grep is still better for exact string/constant search. If you need to find every occurrence of TODO or a specific error code, use grep. code-graph-mcp shines when you need to understand structure, relationships, and code architecture.

📖 Read the full source: r/ClaudeAI