Better Code Review Graph

mcp-name: io.github.n24q02m/better-code-review-graph

Knowledge graph for token-efficient code reviews -- semantic search and call-graph resolution across your codebase.

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An MCP server that parses your codebase with Tree-sitter, builds a structural graph of functions/classes/imports, and gives Claude (or any MCP client) precise context so it reads only what matters instead of the whole tree. Semantic search runs on a local ONNX embedding model by default (zero config, no API key), with an optional cloud embedding chain. Fork of code-review-graph with fixed multi-word search, qualified call resolution, dual-mode embeddings, output pagination, and production CI/CD.

v2.0 migration (BREAKING)

v2.0 adds temporal columns (valid_from_sha / valid_to_sha on every node + edge) and an opt-in security scanner. The schema migration is auto-applied on first GraphStore open, and a backup of the pre-2.0 DB is saved to <graph_db>.pre-2.0.bak so you can roll back. See BREAKING_CHANGES.md for the full schema-change list, behavior changes, environment requirements, and the downgrade procedure (CRG_DOWNGRADE_TO_1_X=1 uv run better-code-review-graph).

Table of contents

• v2.0 migration (BREAKING)
• Install
• Configuration
• Tools
• Features
• Comparison
• Security
• Build from source
• Trust model
• Migration & changelog
• Documentation
• License

Install

The server runs over stdio by default and works with any MCP client. The recommended launcher is uvx (no install step -- it fetches and runs the published package in an isolated environment):

{
  "mcpServers": {
    "better-code-review-graph": {
      "command": "uvx",
      "args": ["--python", "3.13", "better-code-review-graph"],
      "env": { "MCP_TRANSPORT": "stdio" }
    }
  }
}

Or install it as a Python package:

uvx better-code-review-graph        # run without installing
pip install better-code-review-graph

The optional Semgrep engine for deeper security scans is a separate extra:

pip install 'better-code-review-graph[security]'

Install with an AI agent -- paste this to your AI coding agent:

Install MCP server better-code-review-graph following the steps at https://raw.githubusercontent.com/n24q02m/claude-plugins/main/plugins/better-code-review-graph/setup-with-agent.md

Full per-client setup (Claude Code, Codex, Gemini CLI, Cursor, Windsurf, raw mcp.json) is at mcp.n24q02m.com/servers/better-code-review-graph/setup/.

Configuration

Everything works out of the box with zero configuration -- semantic search uses a local qwen3-embed ONNX model (Qwen3-Embedding-0.6B, ~570 MB downloaded on first graph embed). All environment variables below are optional and only needed for cloud embeddings or LLM summaries.

Model chains

Embeddings and summaries are each driven by an ordered model chain -- a CSV of provider/model entries where the order is the litellm fallback order (first entry is the active model). The provider is inferred from the model prefix, so the matching <PROVIDER>_API_KEY is all you need to add.

Variable	Purpose	Empty (default)
EMBEDDING_MODELS	Cloud embedding chain, e.g. jina_ai/jina-embeddings-v5-text-small,gemini/gemini-embedding-001	Local ONNX (qwen3-embed)
SUMMARY_MODELS	Summarizer chain for graph(action="summarize"), e.g. gemini/gemini-2.5-flash,openai/gpt-4o-mini	Summaries disabled

All vectors are stored at a fixed 768 dimensions (MRL truncation), so the embeddings table schema stays valid across providers. Switching embedding model changes the vector space; embeddings are tracked per provider and a provider switch triggers re-embedding rather than mixing incomparable vectors.

Provider API keys

Cloud models need the provider key for whatever prefixes appear in your chains. Without any cloud key the server stays on local ONNX. Summarizers must expose a chat-completion API (so Jina and Cohere are embedding-only).

Model prefix	API key env var	Get a key
jina_ai/	JINA_AI_API_KEY	https://jina.ai/api-key
gemini/	GEMINI_API_KEY (or GOOGLE_API_KEY)	https://aistudio.google.com/apikey
openai/ (or bare text-embedding-*)	OPENAI_API_KEY	https://platform.openai.com/api-keys
cohere/	COHERE_API_KEY	https://dashboard.cohere.com/api-keys

Any other litellm provider works via its standard <PROVIDER>_API_KEY.

Advanced

Variable	Purpose
EMBEDDING_API_BASE	Custom OpenAI-compatible base URL for cloud embedding (SSRF-guarded)
LLM_API_BASE	Custom OpenAI-compatible base URL for the summarizer (SSRF-guarded)
DISABLE_LOCAL_EMBED	Skip the local ONNX download; embedding is unavailable unless a cloud chain is configured
CRG_DATA_DIR	Override the per-user data directory (default ~/.crg) used for per-user graphs and credentials in HTTP multi-user mode
EMBEDDING_BACKEND / EMBEDDING_MODEL / SUMMARY_MODEL	Deprecated singular vars, honored one release with a warning -- migrate to the *_MODELS chains

Example -- cloud embeddings + summaries

{
  "mcpServers": {
    "better-code-review-graph": {
      "command": "uvx",
      "args": ["--python", "3.13", "better-code-review-graph"],
      "env": {
        "MCP_TRANSPORT": "stdio",
        "EMBEDDING_MODELS": "jina_ai/jina-embeddings-v5-text-small,gemini/gemini-embedding-001",
        "SUMMARY_MODELS": "gemini/gemini-2.5-flash",
        "JINA_AI_API_KEY": "jina_...",
        "GEMINI_API_KEY": "AIza..."
      }
    }
  }
}

You can also configure cloud keys interactively in HTTP mode via the relay setup form (config(action="setup_start") returns the browser URL). See the modes overview and multi-user setup.

Tools

Seven tools, each grouping related actions to keep the tool surface small.

graph -- Graph lifecycle

Actions: build | update | stats | embed | export | summarize

Action	Description
build	Full or incremental graph build. Set full_rebuild=true to re-parse all files; pass roots to federate extra repo directories into one graph.
update	Alias for build with full_rebuild=false (incremental).
stats	Graph size, languages, node/edge breakdown, embedding count.
embed	Compute vector embeddings for semantic search. Dual-mode: local ONNX or cloud chain.
export	Export the graph as graphml / json-ld / dot / cypher. Inline or to output_path.
summarize	LLM-generated one-paragraph docstrings for Function nodes (via the SUMMARY_MODELS chain; no-op when no provider key is set). Cost-capped via max_nodes.

query -- Graph queries

Actions: query | search | impact | large_functions | spot_check | renamed_in_diff | diff

Action	Description
query	Predefined patterns: callers_of, callees_of, imports_of, importers_of, children_of, tests_for, inheritors_of, file_summary.
search	Search code entities by name/keyword or semantic similarity.
impact	Blast radius of changed files. Auto-detects from git diff. Paginated with max_results.
large_functions	Find functions/classes exceeding a line-count threshold.
spot_check	Random callsite snippets from the last callers_of/callees_of/inheritors_of/importers_of result.
renamed_in_diff	Symbols whose callsite line shifted versus a base ref.
diff	Nodes added/removed/modified between two commit SHAs (from_sha, to_sha).

Most read actions accept as_of=<sha> for temporal (point-in-time) snapshots and repo=<repo_id> to scope a federated multi-repo graph.

review -- Code review context

Actions: context (default) | delta

Token-optimized review context with structural summary, impacted nodes, source snippets, and review guidance. context auto-detects changed files from the git diff; delta (with from_sha/to_sha, optional show_line_shifts) surfaces refactor moves between two commits.

config -- Server configuration and credential setup

Actions: status | set | cache_clear | setup_status | setup_start | setup_skip | setup_reset | setup_complete

Action	Description
status	Server info: version, graph path, node/edge counts, embedding backend, embeddings count.
set	Update a runtime setting (key=log_level).
cache_clear	Remove all computed embeddings.
setup_status	Show current credential state, providers configured, and setup URL.
setup_start	Start relay setup to configure API keys via browser (HTTP mode).
setup_skip	Set local mode (skip relay permanently, use ONNX only).
setup_reset	Clear credentials and reset state.
setup_complete	Re-resolve credentials from environment variables.

security -- Security scanning

Actions: scan | report | suppress | rule_list

Action	Description
scan	Run a security scan (engine='heuristic' default = 5 regex rules, or 'semgrep'). Findings persist on nodes.security_tags.
report	Re-emit cached findings as JSON (format='json') or SARIF v2.1.0 (format='sarif').
suppress	Suppress a finding by rule_id (or remove=true to un-suppress).
rule_list	List available rules for an engine.

The semgrep engine requires the [security] extra and runs Semgrep's p/auto registry pack plus a 3-rule curated overlay.

help -- Full documentation

Topics: graph | query | review | config | security | recipes

Returns complete documentation for each tool. Use when the compressed descriptions above are insufficient.

config__open_relay -- Re-trigger the relay setup form

Registered automatically from mcp-core. In HTTP mode it returns <PUBLIC_URL>/authorize so the agent can re-open the browser setup form (e.g. after credential expiry); in stdio mode it returns status: 'stdio_unsupported'.

Features

What this fork fixes versus the upstream code-review-graph:

Feature	code-review-graph	better-code-review-graph
Multi-word search	Broken (literal substring)	AND-logic word splitting
callers_of/callees_of	Empty results (bare name targets)	Qualified name resolution + bare fallback
Embedding	sentence-transformers + torch (1.1 GB)	qwen3-embed ONNX + cloud (200 MB), dual-mode
Output size	Unbounded (500K+ chars)	Paginated (max_results, truncated flag)
Tool design	9 individual tools	7 grouped tools: graph + query + review + config + security + help + config__open_relay
Plugin hooks	Invalid PostEdit/PostGit	Valid PostToolUse

Comparison

How better-code-review-graph stacks up against direct competitors in each pillar:

Capability	better-code-review-graph	Greptile	Sourcegraph (Cody / MCP)	CodeGraph (colbymchenry)
Codebase knowledge graph	Yes (Tree-sitter, 14 langs, SQLite)	Yes (functions/classes/deps)	Yes (precise code indexing)	Yes (Tree-sitter, 20+ langs, SQLite)
Persistent incremental updates	Yes (git-diff + file-hash re-parse)	?	Yes (continuous indexing)	Yes (OS file-watcher debounced)
Qualified call resolution (callers/callees)	Yes (same-file bare-call resolution + fallback)	?	Yes (go-to-def / find-references)	Yes (callers / callees / impact)
Semantic search / embeddings	Yes (qwen3 ONNX local + cloud Jina/Gemini/OpenAI/Cohere)	?	Yes (semantic + keyword + regex)	No (FTS5 full-text only)
Token-optimized review context	Yes (review tool, git-diff scoped)	Yes (PR review comments)	No (code-context assistant)	No (context layer, not review)
Security scanning	Yes (Semgrep p/auto + 3-rule overlay, SARIF)	?	?	No
Self-hostable	Yes (stdio default, machine-bound)	Yes (Docker / K8s / air-gapped)	Yes (self-hosted instance)	Yes (100% local, no API keys)
Free / open source	Yes (MIT)	No (proprietary SaaS; free OSS tier)	No (Enterprise license, source private)	Yes (MIT)

Sources: Greptile · Greptile pricing · Sourcegraph MCP · CodeGraph. Cells marked ? are capabilities the competitor does not publicly document, not confirmed absences.

Security

• Graceful fallbacks -- Cloud embedding failure falls back to local ONNX.
• Error handling -- Tools return error strings with fix suggestions, never crash.
• Read-only mount -- Docker mode mounts the repo as :ro (read-only).
• SSRF-guarded endpoints -- Custom EMBEDDING_API_BASE / LLM_API_BASE URLs are validated before any outbound call.

To report a vulnerability, see SECURITY.md.

Build from source

git clone https://github.com/n24q02m/better-code-review-graph
cd better-code-review-graph
uv sync --group dev
uv run pytest
uv run better-code-review-graph

Requirements: Python 3.13, uv.

Trust model

This plugin implements TC-Local (machine-bound, single trust principal). See the mcp-core trust model for full classification.

Mode	Graph DB	Cloud credentials	Who can read your data?
stdio (default)	<repo>/.code-review-graph/graph.db (git-ignored)	~/.better-code-review-graph-mcp/config.json (AES-GCM, machine-bound key)	Only your OS user
HTTP self-host (multi-user)	Per-user ~/.crg/subs/<sub>/graph.db	Per-user ~/.crg/subs/<sub>/config.json	Only the authenticated user

Migration & changelog

The v2.0 release added temporal columns (valid_from_sha / valid_to_sha on every node and edge) plus an opt-in security scanner. The schema migration is auto-applied on first GraphStore open, and a backup of the pre-2.0 DB is written to <graph_db>.pre-2.0.bak. To downgrade and restore it:

CRG_DOWNGRADE_TO_1_X=1 uvx better-code-review-graph

Full schema-change list, behavior changes, and rollback procedure: BREAKING_CHANGES.md. Release-by-release history: CHANGELOG.md.

Documentation

Full docs at mcp.n24q02m.com/servers/better-code-review-graph/setup/:

• Setup -- install methods for Claude Code, Codex, Gemini CLI, Cursor, Windsurf, mcp.json
• Modes overview -- stdio / local-relay / remote-relay / remote-oauth
• Multi-user setup -- per-JWT-sub credential model

Use the help tool from any MCP client for inline per-tool reference.

License

MIT -- See LICENSE.