mcp-server-gpt-chat

An MCP (Model Context Protocol) server for the OpenAI ChatGPT API. Built in Rust, exposes chat completions, vision, embeddings, and model listing as MCP tools.

Communicates via stdio using JSON-RPC 2.0, like all MCP servers.

Tools

Tool	Description
chat	Send a chat completion request to ChatGPT with optional multi-turn history, system prompt, structured output (JSON schema), and model selection
chat_with_vision	Analyse an image with ChatGPT's vision capabilities given an image URL and text prompt
embedding	Generate text embeddings using OpenAI's embedding model
list_models	List all available OpenAI models and their IDs

chat

Send a chat completion request. Supports multi-turn conversations via a JSON message history array, system prompts, structured output via JSON schema, temperature control, and model selection.

Parameters:

Name	Type	Required	Description
prompt	string	yes	The user message to send
model	string	no	Model to use (default: gpt-4o)
system_prompt	string	no	System prompt to set context
messages	string	no	Full conversation history as JSON array of {role, content} objects
temperature	float	no	Sampling temperature (0.0 - 2.0)
max_tokens	integer	no	Maximum tokens to generate
response_schema	string	no	JSON schema string to enforce structured output

chat_with_vision

Analyse an image using ChatGPT's vision capabilities.

Parameters:

Name	Type	Required	Description
prompt	string	yes	Text prompt describing what to analyse
image_url	string	yes	URL of the image (must be http:// or https://)
model	string	no	Model to use (default: gpt-4o)
detail	string	no	Image detail level: low or high (default: high)
temperature	float	no	Sampling temperature (0.0 - 2.0)
max_tokens	integer	no	Maximum tokens to generate

embedding

Generate text embeddings.

Parameters:

Name	Type	Required	Description
input	string	yes	Text to embed as JSON: a single string or array of strings
model	string	no	Embedding model to use (default: text-embedding-3-small)

list_models

List all available OpenAI models. No parameters.

Prerequisites

• Rust (edition 2024)
• An OpenAI API key from platform.openai.com

Setup

Create the config file:

mkdir -p ~/.config/mcp-server-gpt-chat

Create ~/.config/mcp-server-gpt-chat/config.toml:

api_key = "sk-..."

Build

cargo build --release

This produces target/release/gpt-chat.

For development:

cargo build              # debug build
cargo run                # run in dev mode
RUST_LOG=debug cargo run # run with debug logging

MCP Configuration

Add to your Claude Desktop config (~/.config/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "gpt-chat": {
      "command": "/path/to/gpt-chat"
    }
  }
}

Project Structure

src/
  main.rs    - entry point, config loading, stdio transport setup
  server.rs  - MCP tool definitions (chat, chat_with_vision, embedding, list_models)
  api.rs     - OpenAI HTTP client, request/response types, response formatters
  params.rs  - tool parameter types with serde and JSON Schema derives
  config.rs  - TOML config loading

License

MIT