curl-mcp-bridge

A local MCP stdio bridge that proxies MCP JSON-RPC to a Calibress hosted /mcp HTTP endpoint.

This lets any MCP client that supports stdio (Claude Desktop, Roo, etc.) talk to the hosted multi-tenant MCP gateway.

Requirements

• Node.js >= 18

Usage

Set these env vars:

• CALIBRESS_ENDPOINT (required) — Hosted MCP URL (e.g. https://enterprise-plan.dev.calibress.com/mcp)
• CALIBRESS_API_KEY (required) — Tenant/project API key (Bearer). Prefer project-scoped keys so “project selection” is implicit.

Then run:

CALIBRESS_ENDPOINT="https://enterprise-plan.dev.calibress.com/mcp" \
CALIBRESS_API_KEY="cmcp_..." \
node ./bin/curl-mcp-bridge.js

CLI overrides are also available (--endpoint, --api-key, --session-id).

The bridge reads MCP messages from stdin and writes MCP responses to stdout (1 JSON object per line).

Run via npx (npm)

CALIBRESS_ENDPOINT="https://enterprise-plan.dev.calibress.com/mcp" \
CALIBRESS_API_KEY="cmcp_..." \
npx -y @calibress/curl-mcp-bridge@latest

If you need to run an unpublished build, you can still run from GitHub:

CALIBRESS_ENDPOINT="https://enterprise-plan.dev.calibress.com/mcp" \
CALIBRESS_API_KEY="cmcp_..." \
npx -y github:calibress/curl-mcp-bridge

MCP client configuration

Example (Roo / Claude Desktop style):

{
  "curl-mcp-bridge": {
    "transport": "stdio",
    "command": "npx",
    "args": ["-y", "@calibress/curl-mcp-bridge@latest"],
    "env": {
      "CALIBRESS_ENDPOINT": "https://YOUR-TENANT.dev.calibress.com/mcp",
      "CALIBRESS_API_KEY": "cmcp_REPLACE_ME"
    },
    "alwaysAllow": [
      "mcp_version",
      "getting_started",
      "list_surfaces",
      "list_connections",
      "list_operations",
      "get_operation_spec",
      "execute_operation",
      "curl_request"
    ]
  }
}

Session handling

• The hosted MCP endpoint issues Mcp-Session-Id on initialize.
• The bridge caches that session id in-process and automatically sends it on subsequent requests.
• If a client sends a request before initialize, the bridge will bootstrap a session and retry once.

Extensibility

The bridge forwards all JSON-RPC methods as-is.

When the hosted MCP gateway adds new tools (e.g. list_connections), existing clients automatically see them via tools/list without changing the bridge.

Notes

• To publish, bump package.json version and run npm publish (public access is configured).

License

MIT.