Code Assistant

io.github.j0hanzPublished by GitHub account j0hanzv2.0.0Updated Oct 24, 2026

Gemini-powered MCP server for code analysis.

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Overview

AI-generated overview

Gemini-powered local MCP server that reviews diffs and pull requests, analyzes source files, and generates documentation.

What you can do
Code Assistant (Code Lens) runs locally over stdio and uses Google Gemini to analyze code. It captures git diffs and produces PR impact assessments, review summaries, test plans, breaking-change detection, and Big-O complexity analysis. It can cache a source file for refactoring suggestions, code smell detection, documentation stubs, natural-language Q&A, and logic verification through Gemini's code execution sandbox. A standalone web search tool uses Google Search with Grounding.
When to use it
Useful when you want an assistant to help with pull request review, refactoring, documentation, or complexity checks on a local repository. It fits workflows where diffs and files are analyzed before a merge decision, and where up-to-date documentation or API references are needed via web search.
Requirements
Node.js 24 or newer, or Docker. A Gemini API key supplied as GEMINI_API_KEY (falls back to GOOGLE_API_KEY). Network access to the Gemini API. Optional settings include GEMINI_MODEL, MAX_DIFF_CHARS, and task TTL variables.
Before you install
Requires a Gemini API key, which is a billable credential; usage may incur costs. Source code, diffs, and file contents are sent to Google's Gemini API, and web search queries go to Google Search. Diff and file tools cache content server-side. load_file restricts paths to the workspace root, but review the provider's data handling before sending sensitive code.

Installation

In SourceWeft

  1. Open Code Assistant in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

Code Lens MCP Server

[npm version] [License: MIT]

[Install in VS Code] [Install in VS Code Insiders] [Install in Visual Studio]

[Add to LM Studio] [Install in Cursor] [Install in Goose]

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

Overview

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.

Key Features

  • 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

Requirements

Quick Start

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

Docker

bash
docker run -i --rm -e GEMINI_API_KEY="your-api-key" ghcr.io/j0hanz/code-lens

Or with Docker Compose:

bash
GEMINI_API_KEY=your-api-key docker compose up

Client Configuration

Install in VS Code

[Install in VS Code]

Add to .vscode/mcp.json:

json
{  "servers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

Or install via CLI:

sh
code --add-mcp '{"name":"code-lens","command":"npx","args":["-y","@j0hanz/code-lens-mcp@latest"]}'

For more info, see VS Code MCP docs.

Install in VS Code Insiders

[Install in VS Code Insiders]

Add to .vscode/mcp.json:

json
{  "servers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

Or install via CLI:

sh
code-insiders --add-mcp '{"name":"code-lens","command":"npx","args":["-y","@j0hanz/code-lens-mcp@latest"]}'

For more info, see VS Code Insiders MCP docs.

Install in Cursor

[Install in Cursor]

Add to ~/.cursor/mcp.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Cursor MCP docs.

Install in Visual Studio

[Install in Visual Studio]

Add to mcp.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Visual Studio MCP docs.

Install in Goose

[Install in Goose]

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Goose MCP docs.

Install in LM Studio

[Add to LM Studio]

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see LM Studio MCP docs.

Install in Claude Desktop

Add to claude_desktop_config.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Claude Desktop MCP docs.

Install in Claude Code
sh
claude mcp add code-lens -- npx -y @j0hanz/code-lens-mcp@latest

Or add to config:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Claude Code MCP docs.

Install in Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Windsurf MCP docs.

Install in Amp
sh
amp mcp add code-lens -- npx -y @j0hanz/code-lens-mcp@latest

Or add to config:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Amp MCP docs.

Install in Cline

Add to cline_mcp_settings.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Cline MCP docs.

Install in Codex CLI

Add to ~/.codex/config.yaml:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Codex CLI MCP docs.

Install in GitHub Copilot

Add to .vscode/mcp.json:

json
{  "servers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see GitHub Copilot MCP docs.

Install in Warp
json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Warp MCP docs.

Install in Kiro

Add to .kiro/settings/mcp.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Kiro MCP docs.

Install in Gemini CLI

Add to ~/.gemini/settings.json:

json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Gemini CLI MCP docs.

Install in Zed

Add to ~/.config/zed/settings.json:

json
{  "context_servers": {    "code-lens": {      "settings": {        "command": "npx",        "args": ["-y", "@j0hanz/code-lens-mcp@latest"]      }    }  }}

For more info, see Zed MCP docs.

Install in Augment

Add to your VS Code settings.json under augment.advanced:

json
{  "augment.advanced": {    "mcpServers": [      {        "id": "code-lens",        "command": "npx",        "args": ["-y", "@j0hanz/code-lens-mcp@latest"],        "env": {          "GEMINI_API_KEY": "your-api-key"        }      }    ]  }}

For more info, see Augment MCP docs.

Install in Roo Code
json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Roo Code MCP docs.

Install in Kilo Code
json
{  "mcpServers": {    "code-lens": {      "command": "npx",      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],      "env": {        "GEMINI_API_KEY": "your-api-key"      }    }  }}

For more info, see Kilo Code MCP docs.

Use Cases

PR Review Pipeline

  1. Call generate_diff to capture unstaged or staged changes
  2. Run analyze_pr_impact to assess severity and breaking changes
  3. Run generate_review_summary for a risk rating and merge recommendation
  4. Run detect_api_breaking_changes to check for public API breakage
  5. Run generate_test_plan to produce prioritized test cases

Single-File Analysis

  1. Call load_file to cache a source file
  2. Run refactor_code for structural improvement suggestions
  3. Run detect_code_smells for Fowler-taxonomy anti-patterns
  4. Run generate_documentation to generate JSDoc/TSDoc stubs
  5. Use ask_about_code for natural-language Q&A about the file
  6. Use verify_logic to verify algorithms with code execution

Performance Audit

  1. Call generate_diff on a performance-sensitive change
  2. Run analyze_time_space_complexity to detect Big-O degradation

Research

  • Use web_search for up-to-date documentation or API references via Google Search with Grounding

Architecture

text
[MCP Client]    │    │ Transport: stdio    ▼[MCP Server: code-lens]    │ Entry: src/index.ts → src/server.ts    │    ├── initialize / initialized (lifecycle handshake)    │    ├── tools/call ──────────────────────────────────────────────    │   │    │   │ Diff-based tools (require generate_diff first):    │   ├── [generate_diff]              Sync — capture git diff    │   ├── [analyze_pr_impact]          Flash — severity & impact    │   ├── [generate_review_summary]    Flash — risk & merge rec    │   ├── [generate_test_plan]         Flash — test cases    │   ├── [analyze_time_space_complexity] Flash — Big-O analysis    │   ├── [detect_api_breaking_changes]  Flash — API breakage    │   │    │   │ File-based tools (require load_file first):    │   ├── [load_file]                  Sync — cache source file    │   ├── [refactor_code]              Flash — refactoring    │   ├── [detect_code_smells]         Flash — smell detection    │   ├── [generate_documentation]     Flash — doc stubs    │   ├── [ask_about_code]             Flash — Q&A    │   ├── [verify_logic]               Flash — code execution    │   │    │   │ Standalone:    │   └── [web_search]                 Flash — Google Search    │    ├── resources/read ──────────────────────────────────────────    │   ├── [internal://instructions]        Server usage guide    │   ├── [internal://tool-catalog]        Tool reference    │   ├── [internal://workflows]           Workflow sequences    │   ├── [internal://server-config]       Runtime config    │   ├── [internal://tool-info/{name}]    Per-tool details    │   ├── [internal://diff/current]        Cached diff (text/x-patch)    │   └── [internal://file/current]        Cached source file    │    ├── prompts/get ─────────────────────────────────────────────    │   ├── [get-help]           Full server instructions    │   ├── [review-guide]       Tool + focus area workflow    │   ├── [select-workflow]    Pipeline by change type    │   ├── [analyze-file]       File analysis pipeline    │   └── [tool-chain]         Tool prerequisite chain    │    └── Capabilities: structured output, tool annotations, notifications

Request Lifecycle

text
[Client] -- initialize {protocolVersion, capabilities} --> [Server][Server] -- {protocolVersion, capabilities, serverInfo} --> [Client][Client] -- notifications/initialized --> [Server][Client] -- tools/call {name, arguments} --> [Server][Server] -- notifications/progress {token, progress, total} --> [Client][Server] -- {content, structuredContent, isError?} --> [Client]

Task Lifecycle

  • generate_diff and load_file are sync-only. All other tools advertise taskSupport: optional.
  • Requestors may supply a task TTL. The server uses that value up to MAX_TASK_TTL_MS, or falls back to TASK_TTL_MS when omitted.
  • Cancelled tasks remain terminal as cancelled, and tasks/result returns a cancellation-shaped tool result.

MCP Surface

Tools

ToolDescriptionPrerequisiteModel
generate_diffCapture git diff (unstaged/staged) and cache server-side—Sync
analyze_pr_impactAssess severity, categories, breaking changes, rollback complexitygenerate_diffFlash
generate_review_summaryPR summary, risk rating, merge recommendationgenerate_diffFlash
generate_test_planPrioritized test cases and coverage guidancegenerate_diffFlash
analyze_time_space_complexityBig-O complexity analysis and degradation detectiongenerate_diffFlash
detect_api_breaking_changesDetect breaking API/interface changesgenerate_diffFlash
load_fileCache a source file for analysis tools—Sync
refactor_codeComplexity, duplication, naming, grouping suggestionsload_fileFlash
detect_code_smellsStructural code smells (Fowler taxonomy)load_fileFlash
generate_documentationJSDoc/TSDoc/docstring stubs for public exportsload_fileFlash
ask_about_codeNatural-language Q&A about a cached fileload_fileFlash
verify_logicVerify algorithms via Gemini code execution sandboxload_fileFlash
web_searchGoogle Search with Grounding—Flash

Resources

URIDescriptionMIME
internal://instructionsComplete server usage instructionstext/markdown
internal://tool-catalogTool reference: models, params, outputs, data flowtext/markdown
internal://workflowsRecommended workflows and tool sequencestext/markdown
internal://server-configRuntime configuration and limitstext/markdown
internal://tool-info/{toolName}Per-tool details (parameterized)text/markdown
internal://diff/currentMost recently generated difftext/x-patch
internal://file/currentMost recently loaded source filetext/plain

Prompts

PromptDescription
get-helpFull server instructions: capabilities, tools, resources, constraints
review-guideWorkflow guide for a specific tool and focus area
select-workflowRecommended tool pipeline based on change type
analyze-fileGoal-based tool pipeline for single-file analysis
tool-chainFull prerequisite chain for a given tool

MCP Capabilities

Tool Annotations

All tools expose MCP tool annotations:

AnnotationUsed
readOnlyHintYes
destructiveHintYes
idempotentHintYes
openWorldHintYes

Structured Output

All Gemini-powered tools return validated structuredContent alongside text content, using Zod v4 output schemas.

Configuration

VariableDefaultDescription
GEMINI_API_KEY—Required. Gemini API key. Falls back to GOOGLE_API_KEY.
GEMINI_MODELgemini-3-flash-previewOverride the default Gemini model for all tools.
MAX_DIFF_CHARS120000Maximum diff size in characters.
MAX_CONCURRENT_CALLS10Maximum concurrent Gemini API calls.
MAX_CONCURRENT_BATCH_CALLS2Maximum concurrent batch Gemini calls.
MAX_CONCURRENT_CALLS_WAIT_MS2000Wait timeout for concurrency semaphore.
TASK_TTL_MS300000Default task result retention in milliseconds when the request does not specify task.ttl.
MAX_TASK_TTL_MS3600000Upper bound for request-provided task TTL. Set to 0 to remove the cap.
GEMINI_BATCH_MODEoffEnable Gemini batch mode.
GEMINI_HARM_BLOCK_THRESHOLDBLOCK_NONESafety filter threshold (BLOCK_NONE, BLOCK_ONLY_HIGH, BLOCK_MEDIUM_AND_ABOVE, BLOCK_LOW_AND_ABOVE).
GEMINI_DIFF_CACHE_ENABLEDfalseEnable Gemini context caching for large diffs.
GEMINI_DIFF_CACHE_TTL_S3600Cache TTL in seconds (when caching is enabled).

CLI Flags

bash
npx @j0hanz/code-lens-mcp@latest --model gemini-2.5-flash --max-diff-chars 200000
FlagEnv Equivalent
--model, -mGEMINI_MODEL
--max-diff-charsMAX_DIFF_CHARS

Security

ControlStatus
Input validationZod v4 schema validation on all tool inputs
Path safetyload_file restricts paths to workspace root
Stdout safetyLogs to stderr; stdout reserved for MCP protocol
Non-root containerDocker runs as dedicated mcp user

Development

bash
npm install          # Install dependenciesnpm run build        # Compile TypeScriptnpm run dev          # Watch modenpm run dev:run      # Run with --watch and .envnpm run start        # Run compiled servernpm run type-check   # Type-check src + testsnpm run lint         # ESLintnpm run test         # Run test suitenpm run format       # Prettiernpm run inspector    # MCP Inspectornpm run knip         # Dead code detection

Build and Release

  • CI: .github/workflows/release.yml
  • Docker: Multi-stage build (Dockerfile) with node:24-alpine
  • Docker Compose: docker-compose.yml
  • npm: Published as @j0hanz/code-lens-mcp

Troubleshooting

  • Missing API key: Set GEMINI_API_KEY or GOOGLE_API_KEY in your environment or client config env block.
  • "E_NO_DIFF" errors: Call generate_diff before running any diff-based review tool.
  • "E_NO_FILE" errors: Call load_file before running any file analysis tool.
  • Large diffs truncated: Increase MAX_DIFF_CHARS (default: 120,000 characters).
  • Stdout noise: Ensure no other processes write to stdout; the server uses stdio transport.

Credits

Contributing and License

MIT License. See LICENSE for details.

Contributions welcome via pull requests.

Source: README.md at commit 576b329

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v2.0.0LatestSep 16, 2026

Score

40% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

    Declare a license in the repository or the registry entry.