Yellhorn MCP
About
An MCP server that integrates Gemini 2.5 Pro and OpenAI models for software development tasks, allowing the use of your entire codebase as context.
Details
- Author
- msnidal
- GitHub stars
- 14
- Downloads
- 342
- Categories
- Developer Tools, AI
Jump to
- Creates detailed workplans posted as GitHub issues
- Judges code diffs against the original workplan
- Seamless GitHub integration with labeled issues and sub‑issues
- .yellhornignore file to exclude files from AI context
- MCP resources for listing and retrieving workplans
- Google Search Grounding enabled by default for Gemini models
Setting up with Highlight
This MCP is not yet compatible with Highlight’s one-click setup. However, you can still use it with Highlight by following these steps:
- Download and install Highlight from highlightai.com/download
- Navigate to the plugins tab and select "Add Custom Plugin"
-
Configure the plugin with the settings below
Plugin Name
Yellhorn MCPCommand (node, npx, python, etc.)Please refer to the README for specific instructions on how to obtain API keys or other required environment variables.
- Enable "Start Automatically" if you want the plugin to start when Highlight launches
From the repository
Install via uv sync --group dev or uv pip install yellhorn-mcp. Set environment variables GEMINI_API_KEY, OPENAI_API_KEY, XAI_API_KEY, REPO_PATH, and optionally YELLHORN_MCP_MODEL and YELLHORN_MCP_SEARCH. The GitHub CLI (gh) must be installed and authenticated. Configure the server in your MCP client (Codex CLI, VSCode/Cursor, or Claude Code) using a config.toml or mcp.json file with command uv run yellhorn-mcp.
Claude Desktop / Cursor
Paste into your MCP client config file to install this server.
{
"mcpServers": {
"yellhorn mcp": {
"yellhorn-mcp": {
"command": "uv",
"args": [
"sync",
"--group",
"dev"
]
}
}
}
}McpServers
{
"yellhorn-mcp": {
"command": "uv",
"args": [
"sync",
"--group",
"dev"
]
}
}Yellhorn MCP
A Model Context Protocol (MCP) server that provides functionality to create detailed workplans to implement a task or feature. These workplans are generated with a large, powerful model (such as gemini 2.5 pro or even the o3 deep research API), insert your entire codebase into the context window by default, and can also access URL context and do web search depending on the model used. This pattern of creating workplans using a powerful reasoning model is highly useful for defining work to be done by code assistants like Claude Code or other MCP compatible coding agents, as well as providing a reference to reviewing the output of such coding models and ensure they meet the exactly specified original requirements.
Features
- Create Workplans: Creates detailed implementation plans based on a prompt and taking into consideration your entire codebase, posting them as GitHub issues and exposing them as MCP resources for your coding agent
- Judge Code Diffs: Provides a tool to evaluate git diffs against the original workplan with full codebase context and provides detailed feedback, ensuring the implementation does not deviate from the original requirements and providing guidance on what to change to do so
- Seamless GitHub Integration: Automatically creates labeled issues, posts judgement sub-issues with references to original workplan issues
- Context Control: Use .yellhornignore files to exclude specific files and directories from the AI context, similar to .gitignore
- MCP Resources: Exposes workplans as standard MCP resources for easy listing and retrieval
- Google Search Grounding: Enabled by default for Gemini models, providing search capabilities with automatically formatted citations in Markdown
- Automatic Chunking: Handles large codebases that exceed model context limits by intelligently splitting prompts
- Rate Limit Handling: Robust retry logic with exponential backoff for rate limits and transient failures
- Cost Tracking: Real-time cost estimation and usage tracking for all API calls
- Multi-Model Support: Unified interface supporting OpenAI (GPT-4o, GPT-5, o3, o4-mini), xAI Grok (Grok-4, Grok-4 Fast), and Gemini (2.5-pro, 2.5-flash) models with reasoning mode support for GPT-5
Installation
Project bootstrap (uv)
```bash
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