MCP Server with OpenAI-Compatible Model Support

A small, readable Model Context Protocol server that exposes a handful of tools to any MCP client (Goose, Claude Desktop, OpenAI Agents, etc.). It supports both stdio and streamable HTTP transports, and one of its tools streams output from an OpenAI-compatible model.

Tools

The filesystem tools (list_directory, read_file) only make sense over stdio, because the server runs on the user's own machine and can reach their disk — the canonical "local" MCP use case.

Related MCP server: MCP Server

Architecture

• src/server.ts — bootstraps the server, registers tools, selects the transport

• src/config.ts — loads environment configuration

• src/providers/ — OpenAI-compatible client

• src/tools/ — one file per tool

Transports

Set MCP_TRANSPORT to choose how clients reach the server:

generate_text streams its tokens as notifications/message. Over HTTP these ride the single request's own SSE response, so the server stays stateless (no session affinity needed).

Setup

npm install
cp .env.example .env   # then fill in your provider settings
npm run build
npm start

Environment variables (see .env.example):

MCP_TRANSPORT=stdio              # stdio | http | both
MCP_HTTP_HOST=127.0.0.1
MCP_HTTP_PORT=3000
OPENAI_API_KEY=...               # only needed for generate_text
OPENAI_BASE_URL=https://api.openai.com/v1
OPENAI_MODEL=gpt-4o-mini

Testing with Goose

Goose is an open-source AI agent (by Block) that speaks MCP. It uses its own LLM as the "brain" to decide which of your tools to call. See the Goose docs and repo.

1. Give Goose a brain (its own LLM)

Goose needs an LLM provider — this is separate from this server's OPENAI_* config. Using Anthropic as an example, run it inline so the values reach Goose:

export GOOSE_DISABLE_KEYRING=1        # read secrets from env instead of the OS keychain
export GOOSE_PROVIDER=anthropic
export GOOSE_MODEL=claude-sonnet-4-6
export ANTHROPIC_API_KEY=sk-ant-...

(Or run goose configure to store these in the keychain once.)

2. Launch a session with this server attached

npm run build
goose session --with-extension 'node /absolute/path/to/dist/server.js'

Goose calls MCP servers extensions; the tools appear namespaced (e.g. echo, list_directory).

To test the HTTP transport instead, start the server first and point Goose at the URL:

# terminal 1
MCP_TRANSPORT=http MCP_HTTP_PORT=3000 node dist/server.js
# terminal 2
goose session --with-streamable-http-extension 'http://127.0.0.1:3000/'

3. Ask in plain English — the brain picks the tool

You don't name the tool; Goose decides:

echo the words "it works"
list the files in /absolute/path/to/src/tools
read the package.json in this project and tell me the version
what model is the server configured to use?
is the server healthy?

Note: the agent may sometimes prefer one of its own built-in tools over yours (e.g. it may run a shell ls instead of list_directory). That's the brain choosing — phrase the request toward your tool, or disable conflicting built-ins, if you want to force it.

Screenshots

echo — Goose's brain calls the echo tool and reports the result:

Listing files in the project:

Inspecting without an agent

To poke the server directly (no LLM needed):

# Browser UI:
npx @modelcontextprotocol/inspector node dist/server.js

# Raw JSON-RPC over HTTP (server in http mode):
curl -s -X POST http://127.0.0.1:3000/ \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Example stdio client config

{
  "mcpServers": {
    "mcp-openai-server": {
      "command": "node",
      "args": ["/absolute/path/to/dist/server.js"],
      "env": {
        "OPENAI_API_KEY": "your-key",
        "OPENAI_BASE_URL": "https://api.openai.com/v1",
        "OPENAI_MODEL": "gpt-4o-mini"
      }
    }
  }
}