Code Review Graph — Token-Efficient Codebase Context via MCP

Cut AI token usage substantially on large codebases by giving the AI a structural map instead of letting it read everything. Savings scale with codebase size — marginal on small projects, large on monorepos.

Overview

code-review-graph is an MCP server that uses Tree-sitter to parse your codebase into an AST graph stored in SQLite. When your AI assistant needs context for a task, it queries the graph first — getting only the files in the blast radius of your change — instead of reading every file in the directory.

Token Impact (illustrative — varies by codebase):

Quality angle: scoping the AI to the blast radius reduces noise, which tends to improve review focus. Measure on your own repo rather than relying on a fixed multiplier.

Bootstrap Protocol (opt-in)

When invoked during /plan or standard usage on a mid-to-large project, check whether graph analysis is available before relying on it:

1. Step 1: Check if the tool is installed: Get-Command code-review-graph (Windows) or which code-review-graph (macOS/Linux).
2. Step 2: Check if a .code-review-graph/ directory exists in the workspace.
3. Step 3: If installed but the index is missing, ask the user before running code-review-graph build (it scans the whole project).
4. Step 4: If not installed and the project is large, ask the user: "Would you like to pip install code-review-graph and build a local map to cut token usage for this project?" Never install or run build without confirmation.

When to Use vs When to Skip

✅ Install it if:

• Codebase is 500+ files
• You make multi-file changes with cross-module dependencies
• You spend $20+/month on AI assistant tokens
• You work with monorepos, microservices, or cross-package TypeScript
• You want better review quality in addition to cost savings

❌ Skip it if:

• Codebase is under ~200 files with isolated single-file changes
• Heavy use of dynamic patterns (reflection, runtime code gen, dynamic imports)
• You want zero-maintenance — the graph needs to stay in sync
• Team hasn't standardized on an AI coding tool yet

⚠️ Evaluate first if:

• Codebase is 200–500 files — benchmark before committing
• Mix of static and dynamic patterns — test on representative commits

How It Works (4 Layers)

Layer 1: PARSE    → Tree-sitter builds ASTs from 19 languages
Layer 2: STORE    → Nodes + edges saved in SQLite graph
Layer 3: TRACE    → BFS computes blast radius of changes
Layer 4: SERVE    → MCP exposes graph to AI assistants

What the Graph Contains

• Nodes: Files, functions, methods, classes, imports, tests
• Edges: "A calls B", "X imports Y", "TestZ covers FunctionW", "ClassA extends ClassB"
• Metadata: Name, type, file path, line range per node
• Privacy: Structural metadata only — NO source code content in the graph

Supported Languages (19)

Python, TypeScript, JavaScript, Go, Rust, Java, C#, Ruby, Kotlin, Swift, PHP, C/C++, Vue SFC, Solidity, Dart, R, Perl, Lua, Jupyter/Databricks notebooks.

Installation

Prerequisites

• Python 3.9+ (python3 --version)
• pip or pipx installed
• An MCP-compatible AI client (AG Kit, Claude Code, Cursor, Windsurf, Zed)
• Git-tracked codebase (for incremental updates)

Step 1: Install the Package

# Recommended: isolated environment
pipx install code-review-graph

# Alternative: fastest, no permanent install
uvx code-review-graph install

# Alternative: global pip
pip install code-review-graph

Step 2: Configure MCP Client

# Auto-detect all supported tools
code-review-graph install

# Or target a specific platform
code-review-graph install --platform claude-code
code-review-graph install --platform cursor
code-review-graph install --platform windsurf

Restart your editor after this step. The MCP server activates on restart.

Step 3: Build the Initial Graph

cd /your/project
code-review-graph build

Step 4: Enable Watch Mode (Recommended)

# Keep graph current as you work
code-review-graph watch

Incremental updates complete in under 2 seconds. If you prefer manual updates:

code-review-graph update

Step 5: Verify Integration

Open your AI client and check MCP connection. For Claude Code: run /mcp and confirm code-review-graph appears.

Configuration

Ignore File

Create .code-review-graphignore at project root (uses .gitignore syntax):

# Build artifacts
dist/**
.next/**
build/**

# Dependencies
node_modules/**
vendor/**

# Generated files
generated/**
*.generated.ts
*.min.js

# Test fixtures (if large)
__fixtures__/**

Excluding generated files and build artifacts is critical — they inflate the graph with meaningless nodes.

Multi-Repo Setup

For microservice architectures:

# Register additional repos
code-review-graph register /path/to/other/repo

# List all registered repos
code-review-graph repos

The MCP server serves context across all registered repositories.

Core Workflows

1. Blast Radius Analysis (Primary Use)

This is automatic when the MCP server is active. Your AI assistant queries the graph before reading files, getting only the impacted files instead of everything.

Without graph:  Changed auth/middleware.py → AI reads 200+ files → 8,200 tokens
With graph:     Changed auth/middleware.py → Graph returns 12 impacted files → 1,000 tokens

2. Risk-Scored Change Analysis

code-review-graph detect-changes

Scores each uncommitted change by risk level:

• Number of dependents
• Test coverage gaps
• Whether changed functions are on critical paths
• High-risk changes flagged before you ask for review

3. Dead Code Detection

The graph finds nodes with no incoming edges — no callers, no importers, no test coverage:

# Surfaces functions/classes that are candidates for removal
# Useful on mature codebases to reduce cruft

4. Refactoring Preview

code-review-graph rename preview --from OldClassName --to NewClassName

Shows every file affected by a rename, and flags edge cases (dynamic string references that static analysis can't catch).

5. Architecture Visualization

code-review-graph visualize

Generates interactive visualization showing module clusters using community detection (Leiden algorithm). Useful for:

• Onboarding new contributors
• Identifying architectural drift
• Spotting overly-coupled modules

6. Wiki Generation

code-review-graph wiki

Generates markdown wiki of codebase structure — every module, its public API, dependencies, and test coverage.

Known Limitations

Alternatives Comparison

Integration with AG Kit

Complementary Skills

Recommended Session Architecture

1. Start fresh session for each distinct task
2. Graph pre-filters context → AI reads only blast radius
3. Context compression summarizes completed phases
4. Memory system saves key decisions for next session
5. Result: minimum tokens, maximum quality

Best Practices

1. Always run watch mode in development — stale graphs produce stale context
2. Exclude generated files — they inflate the graph with noise
3. Benchmark first — measure token usage for 1 week without, 1 week with
4. Combine with output constraints — graph reduces input, prompt engineering reduces output
5. Use .code-review-graphignore for build artifacts, node_modules, dist/
6. Keep sessions short — fresh sessions + graph = optimal token efficiency
7. Multi-repo registration for microservice architectures