ChatGPT MCP Server

A local MCP (Model Context Protocol) server that gives Claude Code access to specialized ChatGPT review and advisory tools.

The server provides structured second-opinion workflows for:

• General questions and alternative viewpoints
• Implementation plan reviews
• Code reviews
• Debugging investigations
• Architecture reviews

Claude Code remains the primary coding agent. ChatGPT acts only as an advisor and reviewer.

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Purpose

This project combines the strengths of both models:

• Claude Code performs implementation, editing, refactoring, testing, and repository operations.
• ChatGPT provides independent analysis, review, risk assessment, debugging assistance, and architectural feedback.

The goal is to improve decision quality without introducing autonomous behaviour.

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Non-Goals

The server must not:

• Modify files
• Run shell commands
• Access Git automatically
• Deploy anything
• Send entire repositories by default
• Send secrets
• Make autonomous decisions

ChatGPT only returns analysis and recommendations.

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Architecture

Claude Code
    ↓
MCP Tool
    ↓
Input Validation
    ↓
Context Budget Enforcement
    ↓
Prompt Builder
    ↓
Provider Factory (createChatProvider)
    ↓
OpenAI Provider → OpenAI Responses API
    ↓
Advisory Response

The provider layer is configurable via CHATGPT_MCP_PROVIDER env var. Two providers are available:

Value	Description	Use case
openai	Default — calls ChatGPT via OpenAI API	Automated second-opinion queries
manual	Copy-paste — wraps prompts in a ready-to-copy format	Manual ChatGPT Web/Business as advisor

For the manual provider, set CHATGPT_MCP_PROVIDER=manual. Each tool call returns a copy-ready prompt block you can paste into ChatGPT Web or ChatGPT Business. This turns Claude Code into an orchestrator: it builds the perfect prompt and formats it for you to hand off to ChatGPT as a second-opinion advisor — all without API calls, quotas, or cost.

The factory pattern enables future providers (Ollama, Anthropic, custom) without touching tool handlers.

All responses are advisory only.

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Available MCP Tools

Tool	Purpose
ask_chatgpt	General second-opinion questions, alternatives, risks, trade-offs, and clarification.
review_plan	Reviews implementation plans for missing steps, sequencing issues, unsafe assumptions, scope creep, and test gaps.
review_code	Reviews code snippets, patches, and diffs for correctness, bugs, maintainability, security concerns, and testing opportunities.
debug_issue	Analyses errors, logs, failed tests, and stack traces to identify likely root causes and propose safe investigation steps.
architecture_review	Reviews architecture decisions, system design, trade-offs, maintainability, operational risk, vendor lock-in, and future evolution paths.

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Features

OpenAI Integration

• OpenAI Responses API
• Configurable model selection
• Dependency-injected design for testability
• Structured error handling
• Safe error messages without secret leakage

Prompt System

• Shared base prompt layer
• Tool-specific prompt builders
• Consistent advisory behaviour
• Structured response guidance

Input Protection

• Zod-based validation
• Context budget enforcement
• File size limits
• Log size limits
• Secret redaction utilities

MCP Integration

• MCP stdio server
• Tool discovery via tools/list
• Structured tool responses
• Claude Code integration

Testing

• 523+ automated tests
• Unit-tested utilities
• Prompt builder coverage
• OpenAI integration coverage
• Tool handler orchestration coverage
• MCP registration verification

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Requirements

• Node.js 20+
• OpenAI API key
• Claude Code (or another MCP-compatible client)

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Installation

Install dependencies:

npm install

Set your OpenAI API key:

export OPENAI_API_KEY=sk-your-key

Optional environment variables:

export OPENAI_MODEL=gpt-5.1
export OPENAI_TEMPERATURE=0.2

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Running Tests

npm test

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Running the MCP Server

Start the stdio MCP server:

npm start

The server communicates over stdin/stdout and is intended to be launched by an MCP client rather than directly by users.

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Claude Code Configuration

Configure Claude Code to discover the MCP server.

Create either:

• Global configuration: ~/.claude/settings.json
• Project-local configuration: .claude/settings.local.json

Example:

{
  "mcpServers": {
    "chatgpt-mcp": {
      "command": "npm",
      "args": ["start"]
    }
  }
}

After opening the project in Claude Code, the server should be automatically discovered and the five MCP tools should become available.

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Current Status

MVP Complete

Implemented:

• OpenAI Responses API integration
• Shared validation and safety utilities
• Context budget management
• Five prompt builders
• Five tool handlers
• MCP stdio server
• Registration of all five MCP tools
• Claude Code integration documentation
• Comprehensive automated test suite (523+ tests)

Next Steps

Planned future work includes:

• Real-world workflow validation
• Prompt refinements
• Additional context-loading features
• Improved operational diagnostics
• Production hardening

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Development Philosophy

Keep the system simple.

• Prefer local-first solutions
• Minimise moving parts
• Avoid unnecessary abstractions
• Favour small, testable modules
• Keep ChatGPT advisory-only
• Keep Claude Code in control

The objective is not autonomous development. The objective is better engineering decisions through independent review.