Code Lens MCP Server

If you already use Code Lens, the code lens mcp server is the piece that lets your assistant work with it directly. Gemini-powered MCP server for code analysis.

What the server does

Gemini-powered MCP server for automated code review, analysis, and documentation.

Code Lens is a Model Context Protocol server that uses Google Gemini to analyze diffs, review pull requests, detect code smells, generate documentation, and verify logic. It exposes 13 tools, 7 resources, and 5 prompts over stdio transport.

• PR review pipeline — — generate diffs, assess impact, detect breaking API changes, and produce review summaries with merge recommendations
• File analysis — — load any source file for refactoring suggestions, code smell detection, documentation generation, and natural-language Q&A
• Logic verification — — verify algorithms using Gemini's code execution sandbox
• Structured outputs — — all tools return validated JSON via Zod v4 output schemas
• Web search — — Google Search with Grounding for up-to-date information retrieval
• Task lifecycle support — — every tool except load_file can run via MCP tasks with polling, cancellation, and progress updates

Available tools

The toolset is worth reading before you wire it up, because it tells you what the integration is really for:

• generate_diff — Capture git diff (unstaged/staged) and cache server-side
• analyze_pr_impact — Assess severity, categories, breaking changes, rollback complexity
• generate_review_summary — PR summary, risk rating, merge recommendation
• generate_test_plan — Prioritized test cases and coverage guidance
• analyze_time_space_complexity — Big-O complexity analysis and degradation detection
• detect_api_breaking_changes — Detect breaking API/interface changes
• load_file — Cache a source file for analysis tools
• refactor_code — Complexity, duplication, naming, grouping suggestions
• detect_code_smells — Structural code smells (Fowler taxonomy)
• generate_documentation — JSDoc/TSDoc/docstring stubs for public exports
• ask_about_code — Natural-language Q&A about a cached file
• verify_logic — Verify algorithms via Gemini code execution sandbox

Credentials and setup notes

Configuration is passed through the environment: GEMINI_API_KEY, GOOGLE_API_KEY. Treat anything key-shaped as a real credential — scope it to the minimum the server needs, and rotate it if it ever lands in a shared config.

• Node.js >= 24 - A Gemini API key (GEMINI_API_KEY or GOOGLE_API_KEY)

Installation

Installation goes through your MCP client rather than a global install: point it at @j0hanz/code-lens-mcp on npm and it is fetched when the client starts. The copy-paste blocks for Claude Desktop, Claude Code and Cursor are further down this page.

Where it fits

Among the developer tooling options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. Code Lens's toolset — generate_diff, analyze_pr_impact, generate_review_summary and 11 more — is a fair guide to whether it matches your workflow. It is maintained by j0hanz; worth a glance at recent repository activity before you build anything load-bearing on it.

SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.

Worth knowing first

• It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
• With 14 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch Code Lens.
• Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
• Keep per-call confirmation enabled while you learn its behaviour; it is the cheapest safeguard you have.