CodeGraph

MCP (Model Context Protocol) server that builds and exposes a code graph via Neo4j, enabling LLMs to intelligently navigate and analyze codebases.

Why CodeGraph?

LLMs are great at understanding code, but they lack structural awareness. They can read files, but they don't know how classes relate to each other, which functions call which, or what implements what.

CodeGraph solves this by building a knowledge graph of your codebase. Instead of searching through files, the LLM can directly ask: "Who calls this function?", "What classes implement this interface?", or "What would break if I change this?".

The result: faster navigation, fewer hallucinations, and more accurate refactoring suggestions.

Supported Languages

Language	Status
Kotlin	✅ Available
Java	✅ Available
TypeScript/JavaScript	✅ Available

📢 Follow me on LinkedIn to stay updated on new features!

Benchmark Results

Tested on a Kotlin/Quarkus backend, CodeGraph reduces LLM calls, token usage, and costs by 40-50% compared to native file search tools (Glob/Grep/Read).

See the full benchmark report for detailed metrics per scenario.

Quick Start

1. Start Neo4j

docker-compose up -d

Access Neo4j Browser at http://localhost:7474 (Bolt: bolt://localhost:7687)

2. Build the MCP Server

cd mcp-server
npm install
npm run build

3. Index Your Project

cd mcp-server

# Index a project
npx tsx src/scripts/index-project.ts /path/to/project

# With options
npx tsx src/scripts/index-project.ts --clear --exclude-tests /path/to/project

# Dry run (parse and resolve only, skip Neo4j write)
npx tsx src/scripts/index-project.ts --dry-run /path/to/project

💡 Using Claude Code? Use /codegraph:index instead. See Claude Code Plugin.

Options:

Option	Description
--clear	Clear the database before indexing. Use this to start fresh or re-index a project.
--exclude-tests	Exclude test files and directories (*Test.kt, *Spec.kt, /test/, /tests/, etc.).
--dry-run	Parse and resolve symbols without writing to Neo4j. Useful for validating your project parses correctly.

4. Configure Claude Code

Add to your .mcp.json (project-level) or ~/.claude/claude.json (global):

{
  "mcpServers": {
    "codegraph": {
      "command": "node",
      "args": ["/absolute/path/to/codegraph/mcp-server/dist/index.js"],
      "env": {
        "NEO4J_URI": "bolt://localhost:7687",
        "NEO4J_USER": "neo4j",
        "NEO4J_PASSWORD": ""
      }
    }
  }
}

Note: Leave NEO4J_PASSWORD empty if using the default Docker setup (NEO4J_AUTH=none).

Claude Code Plugin

For the best experience with Claude Code, use the CodeGraph plugin with slash commands:

Command	Description
/codegraph:setup	Start Neo4j and prepare the database
/codegraph:index	Index your project into the graph
/codegraph:status	Check Neo4j connection and graph stats

👉 See Claude Code Plugin for installation and usage.

Available MCP Tools

Tool	Description
search_nodes	Search classes, interfaces, functions by name or pattern
get_callers	Find all functions calling a specified function
get_callees	Find all functions called by a specified function
get_neighbors	Get dependencies and dependents of a class/interface
get_implementations	Find implementations of an interface
get_impact	Analyze impact of modifying a node
find_path	Find shortest path between two nodes
get_file_symbols	List all symbols defined in a file

Docker Commands

# Start Neo4j
docker-compose up -d

# Stop Neo4j
docker-compose down

# Stop and remove data
docker-compose down -v

# Check logs
docker-compose logs -f neo4j

License

MIT