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The initialize method is the first request an AI client must send after connecting. It negotiates the protocol version and returns the server’s capabilities, name, and version.

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MCP Endpoint

POST https://yoursite.com/mcp/{slug}/{server_id}
Content-Type: application/json

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Request

curl -X POST \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2024-11-05",
      "capabilities": {
        "roots": {"listChanged": true},
        "sampling": {}
      },
      "clientInfo": {
        "name": "claude-desktop",
        "version": "1.0.0"
      }
    }
  }' \
  "https://yoursite.com/mcp/my-weather-tools/a1b2c3d4e5f6a1b2"

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Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "protocolVersion": "2024-11-05",
    "capabilities": {
      "tools": {
        "listChanged": true
      }
    },
    "serverInfo": {
      "name": "My Weather Tools",
      "version": "1.0.0"
    }
  }
}

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Response Headers

HeaderDescription
Mcp-Session-IdSession ID to use in subsequent requests
Content-Typeapplication/json

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Follow-up Notification

After receiving the initialize response, the client should send the notifications/initialized notification to signal it’s ready: 
{
  "jsonrpc": "2.0",
  "method": "notifications/initialized",
  "params": {}
}
This is a notification (no id field), so no response is expected.

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Capabilities

GetMCP currently reports:
CapabilityValue
tools.listChangedtrue — server can notify when tool list changes