Mcp Stdio To Streamable Http Adapter

What is Mcp Stdio To Streamable Http Adapter about?

A lightweight bridge that runs as a STDIO‑based MCP server and relays all MCP traffic to a configured Streamable HTTP MCP endpoint. By deploying this adapter, existing MCP clients (e.g., Claude Desktop, LibreChat) gain immediate compatibility with the new Streamable HTTP transport without any code changes.

How to use Mcp Stdio To Streamable Http Adapter?

1. Install the package via npx (no global install required).
2. Set the required environment variables – URI (the HTTP endpoint) and optionally MCP_NAME and BEARER_TOKEN.
3. Reference the adapter in the client’s MCP server configuration (Claude Desktop, LibreChat, etc.).
4. Run the client; the adapter will start, read MCP messages from STDIO, forward them over HTTP, and pipe responses back.

Key features of Mcp Stdio To Streamable Http Adapter

• Zero‑code integration – works with any STDIO‑capable MCP client.
• Configurable naming – MCP_NAME allows multiple adapters side‑by‑side.
• Bearer token support – optional Authorization header for secure HTTP servers.
• NPM‑based delivery – run directly with npx or build locally.
• Debugging tools – built‑in script to launch the MCP Inspector for live inspection.

Use cases of Mcp Stdio To Streamable Http Adapter

• Enable Claude Desktop or LibreChat to consume newly released Streamable HTTP MCP services.
• Provide a quick, distributable wrapper for SaaS providers exposing MCP over HTTP.
• Test or develop Streamable HTTP MCP servers locally while still using existing STDIO clients.
• Deploy multiple adapters for different back‑ends (e.g., OpenAI, PyroPrompts) in a single client environment.

FAQ from the Mcp Stdio To Streamable Http Adapter

Q: Do I need to build the project before using it? A: No. The package can be executed directly with npx. Building is only required if you want to run a locally compiled version.

Q: Is the MCP_NAME environment variable mandatory? A: It is optional for a single adapter. When you run multiple adapters in the same client, each must have a unique MCP_NAME.

Q: How is authentication handled? A: Provide a BEARER_TOKEN env var; the adapter adds it as an Authorization: Bearer <token> header on every HTTP request.

Q: Can I use this with non‑Node clients? A: Yes. As long as the client can spawn a process that communicates over STDIO, it can use the adapter regardless of the client language.

Q: Where can I debug communication? A: Run npm run inspector to start the MCP Inspector, which gives a browser UI showing the request/response flow.

mcp-stdio-to-streamable-http-adapter MCP Server

Integrate any MCP Client that has STDIO MCP Server Support (most do) with the Streamable HTTP MCP Servers

If you have a Streamable HTTP MCP Server, forking this, hardcoding the URI and publishing will give you a repo that you can point to, add to directories and let people use via STDIO.

Note: This has similarities to the mcp-remote package

Why?

The MCP Spec to add a Streamable HTTP Transport landed end of March 2025 and as of the end of April, no clients have adopted support. The typescript-sdk has merged the code, but not released. The Python SDK is still in development to support it. The Inspector supports it, but that's it.

This leaves developers in an awkward position. Develop the MCP Server using STDIO or SSE (deprecated) so it works with clients or develop with Streamable HTTP transport, but nobody can use it.

I (ferrants) want to start integrating the Streamable HTTP MCP Servers beyond just the inspector, so I need a way to connect them to clients and LLMs right away!

This package aims to bridge the cap by being a STDIO MCP Server that relays to your Streamable HTTP MCP Server. This makes all MCP Clients support Streamable HTTP right away. And now developers can develop the Streamable HTTP MCP Servers and provide an installation method.

Installation

To add OpenAI to Claude Desktop, add the server config:

On MacOS: ~/Library/Application Support/Claude/claude_desktop_config.json

On Windows: %APPDATA%/Claude/claude_desktop_config.json

Env Vars

• URI: The URL of the Streamable HTTP MCP Server. This is required.
• MCP_NAME: The name of the MCP Server. This is optional. If you configure multiple, this is required so they do not have the same names.
• BEARER_TOKEN: The Bearer token for the Streamable HTTP MCP Server. This is optional. If specified, this will be sent along in the Authorization header.

Configuration

You can use it via npx in your Claude Desktop configuration like this:

{
  "mcpServers": {
    "my-saas-app-development": {
      "command": "npx",
      "args": [
        "@pyroprompts/mcp-stdio-to-streamable-http-adapter"
      ],
      "env": {
        "URI": "http://localhost:3002/mcp",
        "MCP_NAME": "local-custom-streamable-http-adapter"
      }
    }
  }
}

Or, if you clone the repo, you can build and use in your Claude Desktop configuration like this:

{
  "mcpServers": {
    "my-saas-app-development": {
      "command": "node",
      "args": [
        "/path/to/mcp-stdio-to-streamable-http-adapter/build/index.js"
      ],
      "env": {
        "URI": "http://localhost:3002/mcp",
        "MCP_NAME": "local-custom-streamable-http-adapter"
      }
    }
  }
}

You can add multiple providers by referencing the same MCP server multiple times, but with different env arguments:

{
  "mcpServers": {
    "my-saas-app-development": {
      "command": "node",
      "args": [
        "/path/to/mcp-stdio-to-streamable-http-adapter/build/index.js"
      ],
      "env": {
        "URI": "http://localhost:3002/mcp",
        "MCP_NAME": "local-custom-streamable-http-adapter"
      }
    },
    "pyroprompts": {
      "command": "node",
      "args": [
        "/path/to/mcp-stdio-to-streamable-http-adapter/build/index.js"
      ],
      "env": {
        "URI": "https://api.pyroprompts.com/mcp",
        "MCP_NAME": "pyroprompts",
        "BEARER_TOKEN": "abcdefg"
      }
    }
  }
}

With these three, you'll see a tool for each in the Claude Desktop Home:

And then you can chat with other LLMs and it shows in chat like this:

Or, configure in LibreChat like:

  my-saas-app-development:
    type: stdio
    command: npx
    args:
      - -y
      - @pyroprompts/mcp-stdio-to-streamable-http-adapter
    env:
      URI: "http://localhost:3002/mcp",
      MCP_NAME: "my-custom-saas-app"
      PATH: '/usr/local/bin:/usr/bin:/bin'

And it shows in LibreChat:

Development

Install dependencies:

npm install

Build the server:

npm run build

For development with auto-rebuild:

npm run watch

Debugging

Since MCP servers communicate over stdio, debugging can be challenging. We recommend using the MCP Inspector, which is available as a package script:

npm run inspector

The Inspector will provide a URL to access debugging tools in your browser.

Acknowledgements

• Obviously the modelcontextprotocol and Anthropic teams for the MCP Specification and integration into Claude Desktop. https://modelcontextprotocol.io/introduction
• PyroPrompts for sponsoring this project. Use code MCPSTREAMABLEADAPTER for 20 free automation credits on Pyroprompts.