MCP JSON-RPC Message

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://api-evangelist.github.io/mcp/json-schema/mcp-jsonrpc-message-schema.json",
  "title": "MCP JSON-RPC Message",
  "description": "Common envelope for all MCP messages. All MCP traffic uses JSON-RPC 2.0 over stdio or Streamable HTTP transports.",
  "oneOf": [
    { "$ref": "#/$defs/JSONRPCRequest" },
    { "$ref": "#/$defs/JSONRPCResponse" },
    { "$ref": "#/$defs/JSONRPCError" },
    { "$ref": "#/$defs/JSONRPCNotification" }
  ],
  "$defs": {
    "JSONRPCRequest": {
      "type": "object",
      "required": ["jsonrpc", "id", "method"],
      "properties": {
        "jsonrpc": { "const": "2.0" },
        "id": {
          "oneOf": [
            { "type": "string", "minLength": 1 },
            { "type": "integer" }
          ],
          "description": "Request ID. MUST NOT be null and MUST NOT have been previously used by the requestor in this session."
        },
        "method": { "type": "string" },
        "params": { "type": "object" }
      },
      "additionalProperties": false
    },
    "JSONRPCResponse": {
      "type": "object",
      "required": ["jsonrpc", "id", "result"],
      "properties": {
        "jsonrpc": { "const": "2.0" },
        "id": {
          "oneOf": [
            { "type": "string" },
            { "type": "integer" }
          ]
        },
        "result": { "type": "object" }
      },
      "additionalProperties": false
    },
    "JSONRPCError": {
      "type": "object",
      "required": ["jsonrpc", "error"],
      "properties": {
        "jsonrpc": { "const": "2.0" },
        "id": {
          "oneOf": [
            { "type": "string" },
            { "type": "integer" },
            { "type": "null" }
          ]
        },
        "error": {
          "type": "object",
          "required": ["code", "message"],
          "properties": {
            "code": { "type": "integer" },
            "message": { "type": "string" },
            "data": {}
          },
          "additionalProperties": false
        }
      },
      "additionalProperties": false
    },
    "JSONRPCNotification": {
      "type": "object",
      "required": ["jsonrpc", "method"],
      "properties": {
        "jsonrpc": { "const": "2.0" },
        "method": { "type": "string" },
        "params": { "type": "object" }
      },
      "not": { "required": ["id"] },
      "additionalProperties": false
    }
  }
}