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System Architecture

How MCP Communication Works

MCP uses JSON-RPC 2.0 over HTTP. Here is the request/response flow:

1. Tool Discovery -- The AI agent asks what tools are available:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

2. Tool Call -- The agent invokes a specific tool:

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "search_products",
    "arguments": {
      "category": "Electronics",
      "max_price": 500
    }
  }
}

3. Response -- The server returns results via Server-Sent Events (SSE):

event: message
data: {"jsonrpc":"2.0","id":2,"result":{"content":[{"type":"text","text":"[{\"id\":1,\"name\":\"Wireless Mouse\",...}]"}]}}

The transport layer used on Supabase Edge Functions is WebStandardStreamableHTTPServerTransport, which implements the MCP Streamable HTTP specification -- an HTTP-based transport that supports both request/response and server-initiated streaming via SSE.

Next: Module 3 - Setting Up Your Supabase Project →