Overview
The mcp action turns SBproxy into an MCP gateway. It accepts JSON-RPC 2.0 over HTTP, presents one endpoint to MCP clients (Claude Desktop, agent runtimes, custom hosts), and forwards tools/call requests to one or more upstream MCP servers.
Today the action operates exclusively as a federating gateway. To author tools, run a small MCP server (Python, TypeScript, or Go SDK) and federate it under SBproxy.
Capabilities
- Federation. Aggregate
list_toolsfrom one or more upstream MCP servers into a single catalog. - Namespace prefixing. Apply a per-upstream prefix so tool names from different servers don't collide.
- Tool allowlist. Restrict which tools the gateway forwards
tools/callrequests to. - Transport choice.
streamable_httporsseper upstream. - Standard origin features. Authentication, rate limits, audit logging attach the same way they do to any other origin.
Minimal configuration
proxy:
http_bind_port: 8080
origins:
"mcp.example.com":
action:
type: mcp
mode: gateway
server_info:
name: my-mcp
version: "1.0.0"
federated_servers:
- origin: tools.internal
prefix: internal
transport: streamable_http
Test it:
curl -H "Host: mcp.example.com" http://localhost:8080/mcp -H "Content-Type: application/json" -d '{"jsonrpc": "2.0", "method": "initialize", "id": 1}'
Authentication and policy
Attach the standard authentication: block to gate access. Any of the OSS auth providers work: api_key, basic_auth, bearer, jwt, digest, forward_auth, bot_auth. Rate limits, tool allowlists, and audit logging attach the same way they do to any other origin.
See also
- MCP federation reference for the full federation field list.
- Authentication providers
- Rate limiting and tool allowlists