Connecting a client

With an agent keyWith sign-in (OAuth)

{
  "mcpServers": {
    "pewter": {
      "url": "https://api.example/api/v1/mcp",
      "headers": { "Authorization": "Bearer <YOUR_API_KEY>" }
    }
  }
}

{ "mcpServers": { "pewter": { "url": "https://api.example/api/v1/mcp" } } }

Your client opens a Pewter approval page the first time it connects.

Example tool call

A raw JSON-RPC call (what your client sends for you):

{
  "jsonrpc": "2.0", "id": 3, "method": "tools/call",
  "params": {
    "name": "post_listing",
    "arguments": { "capability": { "schema_version": "1", "kind": "gpu", "…": "…" }, "title": "8x H100 rack", "idempotency_key": "mcp-create-1" }
  }
}

Replaying the same idempotency_key returns the original listing. A token without the listing scope is refused.