code-graph-mcp
A high-performance code knowledge graph server implementing the Model Context Protocol (MCP). Indexes codebases into a structured AST knowledge graph with semantic search, call graph traversal, and HTTP route tracing — designed to give AI coding assistants deep, structured understanding of your code.
Features
- Multi-language parsing — Tree-sitter AST extraction across tiers of depth:
- Full (calls + imports + inheritance + HTTP routes + test markers): TypeScript/TSX, JavaScript, Go, Python, Rust, Java
- Smoke-tested (calls + imports + inheritance): C#, Kotlin, Ruby, PHP, Swift, Dart
- Limited (functions + calls +
#include imports + gtest test markers; Class::method scope qualification deferred): C, C++
- Scripting: Bash (functions + commands +
source/. imports), Markdown (headings)
- File-FTS only (no AST symbol extraction): HTML, CSS, JSON
- Semantic code search — Hybrid BM25 full-text + vector semantic search with Reciprocal Rank Fusion (RRF), powered by sqlite-vec
- Call graph traversal — Recursive CTE queries to trace callers/callees with cycle detection
- HTTP route tracing — Map route paths to backend handler functions (Express, Flask/FastAPI, Go
net/http)
- Dead code detection — Find unreferenced symbols with smart Orphan/Exported-Unused classification
- Impact analysis — Determine the blast radius of code changes by tracing all dependents
- Incremental indexing — Merkle tree change detection with file system watcher for real-time updates. Smart event filtering skips metadata-only changes (chmod, xattr)
- Context compression — Token-aware snippet extraction for LLM context windows (L0→full code, L1→summaries, L2→file groups, L3→directory overview). Compact JSON output saves 15-20% tokens
- Embedding model — Optional local embedding via Candle (feature-gated
embed-model). Context reordered to prioritize structural relations over code for better embedding quality
- Self-healing — Automatic SQLite corruption recovery with rebuild. Startup repair for incomplete indexing (Phase 3 failures)
- MCP protocol — JSON-RPC 2.0 over stdio, plug-and-play with Claude Code, Cursor, Windsurf, and other MCP clients
- Claude Code Plugin — First-class plugin with slash commands (
/understand, /trace, /impact), agents, skills, auto-indexing hooks, StatusLine integration, and self-updating
Why code-graph-mcp?
Unlike naive full-text search or simple AST dumps, code-graph-mcp builds a structured knowledge graph that understands the relationships between symbols across your entire codebase.
Incremental by Design
BLAKE3 Merkle tree tracks every file's content hash. On re-index, only changed files are re-parsed — unchanged directory subtrees are skipped entirely via mtime cache. When a function signature changes, dirty propagation automatically regenerates context for all downstream callers across files.
Hybrid Search, Not Just Grep
Combines BM25 full-text ranking (FTS5) with vector semantic similarity (sqlite-vec) via Reciprocal Rank Fusion (RRF) with raw score blending — so searching "handle user login" finds the right function even if it's named authenticate_session. Results are auto-compressed to fit LLM context windows.
The parser doesn't just find function calls — it tracks them within their proper scope context. Extracts calls, imports, inheritance, interface implementations, exports, and HTTP route bindings. Same-file targets are preferred over cross-file matches to minimize false-positive edges.
HTTP Request Flow Tracing
Unique to code-graph-mcp: trace from GET /api/users → route handler → service layer → database call in a single query. Supports Express, Flask/FastAPI, and Go HTTP frameworks.
Zero External Dependencies at Runtime
Single binary, embedded SQLite, bundled sqlite-vec extension, optional local embedding model via Candle — no database server, no cloud API, no Docker required. Runs entirely on your machine.
Built for AI Assistants
Every design decision — from token-aware compression to node_id-based snippet expansion — is optimized for LLM context windows. Works out of the box with Claude Code, Cursor, Windsurf, and any MCP-compatible client.
Performance
| Indexing speed | 300+ files/second (single-threaded, release build) |
| Incremental re-index | <250ms no-change detection via BLAKE3 Merkle tree |
| FTS search P50 / P99 | <300us / <1ms |
| Database overhead | ~3.5MB per 800 nodes |
| Token savings | 5-20x fewer tokens per code understanding task vs grep+read |
Run code-graph-mcp benchmark on your own project to measure.
Efficiency: code-graph vs Traditional Tools
Real-world benchmarks comparing code-graph-mcp tools against traditional approaches (Grep + Read + Glob) on a 33-file Rust project (~537 AST nodes).
Tool Call Reduction
| Project architecture overview | 5-8 calls | 1 call (project_map) | ~85% |
| Find function by concept | 3-5 calls | 1 call (semantic_code_search) | ~75% |
| Trace 2-level call chain | 8-15 calls | 1 call (get_call_graph) | ~90% |
| Pre-change impact analysis | 10-20+ calls | 1 call (impact_analysis) | ~95% |
| Module structure & exports | 5+ calls | 1 call (module_overview) | ~80% |
| File dependency mapping | 3-5 calls | 1 call (dependency_graph) | ~75% |
| Similar code detection | N/A | 1 call (find_similar_code) | unique |
Overall Session Efficiency
| Tool calls per navigation task | ~6 | ~1.2 | ~80% fewer |
| Source lines read into context | ~8,000 lines | ~400 lines (structured) | ~95% less |
| Navigation token cost | ~36K tokens | ~7K tokens | ~80% saved |
| Full session token savings | — | — | 40-60% |
What code-graph Uniquely Enables
- Impact analysis — "Changing
conn affects 33 functions across 4 files, 78 tests at HIGH risk" — impossible to derive manually with Grep
- Transitive call tracing — Follow
main → run_serve → handle_message → handle_tools_call → conn in one query
- Semantic search — Find
authenticate_session when searching "handle user login"
- Dependency strength — Not just "file A imports file B", but "file A uses 38 symbols from file B"
When Traditional Tools Are Still Better
| Exact string / constant search | Grep |
| Reading a file to edit it | Read |
| Finding files by name pattern | Glob |
Architecture
src/
├── domain.rs # Shared constants, relation types, env-var config
├── mcp/ # MCP protocol layer (JSON-RPC, tool registry, server)
│ └── server/ # McpServer with IndexingState + CacheState sub-structs
├── parser/ # Tree-sitter parsing, relation extraction, LanguageConfig dispatch
├── indexer/ # 3-phase pipeline, Merkle tree, file watcher
├── storage/ # SQLite schema (v6), CRUD, FTS5, migrations
├── graph/ # Recursive CTE call graph queries
├── search/ # RRF fusion search combining BM25 + vector
├── embedding/ # Candle embedding model (optional, masked mean pooling)
├── sandbox/ # Context compressor with token estimation
└── utils/ # Language detection, config
Installation
Option 1: Claude Code Plugin (Recommended)
Install as a Claude Code plugin for the best experience — includes slash commands, agents, skills, auto-indexing hooks, StatusLine health display, and automatic updates:
/plugin marketplace add sdsrss/code-graph-mcp
/plugin install code-graph-mcp
What you get:
- MCP Server — All code-graph tools available to Claude
- Slash Commands —
/understand <module>, /trace <route>, /impact <symbol>
- Code Explorer Agent — Deep code understanding expert via
code-explorer
- Auto-indexing Hook — Incremental index on every file edit (PostToolUse)
- StatusLine — Real-time health display (nodes, files, watch status) — compatible with other plugins' StatusLine via composite multiplexer
- Auto-update — Checks for new versions every 6h, updates silently
Manual Update
npm update -g @sdsrs/code-graph
Then reconnect the MCP server in Claude Code with /mcp.
Note: Auto-update is disabled in the source repo directory (dev mode). Use manual update when developing the plugin itself.
Invited-memory mode (quieter prompts)
By default, every user prompt the plugin deems code-related gets a small context injection from code-graph CLI output. If you'd rather rely on MEMORY.md + explicit tool calls, opt into invited-memory mode:
Option 2: Claude Code MCP Server Only
Register as an MCP server without the plugin features:
claude mcp add code-graph-mcp -- npx -y @sdsrs/code-graph
Option 3: Cursor / Windsurf / Other MCP Clients
Add to your MCP settings file (e.g. ~/.cursor/mcp.json):
{
"mcpServers": {
"code-graph": {
"command": "npx",
"args": ["-y", "@sdsrs/code-graph"]
}
}
}
Option 4: npx (No Install)
Run directly without installing:
npx -y @sdsrs/code-graph
Option 5: npm (Global Install)
Install globally, then run anywhere:
npm install -g @sdsrs/code-graph
code-graph-mcp
Uninstallation
Claude Code Plugin
/plugin uninstall code-graph-mcp
/plugin marketplace remove code-graph-mcp
node ~/.claude/plugins/cache/code-graph-mcp/code-graph-mcp/*/scripts/lifecycle.js uninstall
Claude Code MCP Server
claude mcp remove code-graph-mcp
Cursor / Windsurf / Other MCP Clients
Remove the code-graph entry from your MCP settings file (e.g. ~/.cursor/mcp.json).
npm (Global)
npm uninstall -g @sdsrs/code-graph
MCP Tools
project_map | Full project architecture: modules, dependencies, entry points, hot functions |
semantic_code_search | Hybrid BM25 + vector + graph search for AST nodes |
get_call_graph | Trace upstream/downstream call chains for a function |
trace_http_chain | Full request flow: route → handler → downstream call chain |
impact_analysis | Analyze the blast radius of changing a symbol |
module_overview | High-level overview of a module's structure and exports |
dependency_graph | Visualize dependency relationships between modules. Supports compact mode |
find_similar_code | Find semantically similar code via embeddings. Requires symbol_name or node_id |
get_ast_node | Extract a specific code symbol with signature, body, and relations. Supports compact mode |
ast_search | Search AST nodes by text and/or structural filters (type, return type, params) |
find_references | Find all references to a symbol (callers, importers, inheritors). Supports compact mode |
find_dead_code | Find unused code — orphan symbols and exported-but-unused public APIs |
CLI Commands
All tools are also available as CLI subcommands for shell scripts, hooks, and terminal workflows:
search <query> | semantic_code_search | FTS5 search by concept |
ast-search [query] | ast_search | Structural search with --type/--returns/--params filters |
callgraph <symbol> | get_call_graph | Show call graph (callers/callees) |
impact <symbol> | impact_analysis | Impact analysis (callers, routes, risk level) |
show <symbol> | get_ast_node | Show symbol details (code, type, signature) |
map | project_map | Project architecture map |
overview <path> | module_overview | Module symbols grouped by file and type |
deps <file> | dependency_graph | File-level dependency graph |
trace <route> | trace_http_chain | Trace HTTP route → handler → downstream calls |
similar <symbol> | find_similar_code | Find semantically similar code (requires embeddings) |
refs <symbol> | find_references | Find all references to a symbol |
dead-code [path] | find_dead_code | Find unused code (orphans and exported-unused) |
grep <pattern> | — | AST-context grep (ripgrep + containing function/class) |
incremental-index | — | Run incremental index update (auto-creates DB if needed) |
health-check | get_index_status | Query index status and freshness |
benchmark | — | Benchmark index speed, query latency, token savings |
Common options: --json (JSON output), --compact (compact output), --limit N, --depth N, --file <path>.
Plugin Slash Commands
Available when installed as a Claude Code plugin:
/understand <module> | Deep dive into a module or file's architecture and relationships |
/trace <route> | Trace a full HTTP request flow from route to data layer |
/impact <symbol> | Analyze the impact scope of changing a symbol before modifying it |
/status | Show code-graph index status and embedding progress |
/rebuild | Force a full code-graph index rebuild |
Supported Languages (16)
| TypeScript | .ts, .tsx | calls, imports, exports, inherits, implements, routes_to |
| JavaScript | .js, .jsx, .mjs, .cjs | calls, imports, exports, inherits, routes_to |
| Go | .go | calls, imports, routes_to |
| Python | .py, .pyi | calls, imports, inherits, routes_to |
| Rust | .rs | calls, imports, inherits, implements |
| Java | .java | calls, imports, inherits, implements |
| C# | .cs | calls, imports, inherits, implements |
| Kotlin | .kt, .kts | calls, imports, inherits |
| Ruby | .rb | calls, imports, inherits |
| PHP | .php | calls, imports, inherits, implements |
| Swift | .swift | calls, imports, inherits |
| Dart | .dart | calls, imports, implements |
| C | .c, .h | calls, imports |
| C++ | .cpp, .cc, .cxx, .hpp | calls, imports, inherits |
| HTML | .html, .htm | structural parsing |
| CSS | .css | structural parsing |
Team-shared graph snapshot
Skip the full local index for team members and CI runners by publishing a
~3-5MB graph snapshot with each GitHub release.
Setup (one-time):
- Copy
node_modules/code-graph-mcp/templates/code-graph-snapshot.yml
into your repo's .github/workflows/.
- Push a release tag. The workflow uploads
code-graph-snapshot-<sha>.db.zst as a release asset.
Verify:
npx code-graph-mcp snapshot inspect ./code-graph-snapshot-<sha>.db.zst
After setup, fresh clones automatically fetch the latest snapshot the
first time the MCP server starts. No client-side configuration needed.
Storage
Uses SQLite with:
- FTS5 for full-text search
- sqlite-vec extension for vector similarity search
- Merkle tree hashes for incremental change detection
Data is stored in .code-graph/index.db under the project root (auto-created, gitignored).
Build from Source
Prerequisites
- Rust 1.75+ (2021 edition)
- A C compiler (for bundled SQLite / sqlite-vec)
Build
cargo build --release
cargo build --release --features embed-model
Direct cargo install users get the FTS5-only build by default. npm/npx/plugin
users get the full hybrid (FTS5 + vector) build automatically — release CI
compiles with --features embed-model for shipped binaries.
Configure (from source)
Add the compiled binary to your MCP settings:
{
"mcpServers": {
"code-graph": {
"command": "/path/to/target/release/code-graph-mcp"
}
}
}
Development
cargo test
cargo test --no-default-features
cargo check
cargo bench --no-default-features
License
See LICENSE for details.