Overview

MCP Gateway

Execute MCP tool calls via the JSON-RPC 2.0 gateway endpoint.

Overview

The MCP Gateway provides a JSON-RPC 2.0 interface for executing tool calls on registered MCP servers. The gateway handles authentication, access control enforcement, request routing, and response normalization.

Gateway endpoint

POST https://mcp-gateway.mythic-analytics.com/rpc

Authentication

Include your MCP API key in the Authorization header.

Authorization: Bearer YOUR_MCP_API_KEY

JSON-RPC 2.0 format

All requests and responses follow the JSON-RPC 2.0 specification.

Request format

{
  "jsonrpc": "2.0",
  "id": "req-001",
  "method": "tools/call",
  "params": {
    "name": "query_analytics",
    "arguments": {
      "client_id": "acme-retail",
      "metric": "page_views",
      "period": "30d"
    }
  }
}

Must be "2.0".

Unique request identifier. Returned in the response for correlation.

body

methodstring

Required

The MCP method to invoke. Use tools/call for tool execution.

body

paramsobject

Required

Method-specific parameters. For tools/call, include name and arguments.

Success response

{
  "jsonrpc": "2.0",
  "id": "req-001",
  "result": {
    "content": [
      {
        "type": "text",
        "text": "{"page_views": 42600, "period": "30d"}"
      }
    ]
  }
}

Error response

{
  "jsonrpc": "2.0",
  "id": "req-001",
  "error": {
    "code": -32600,
    "message": "Invalid request",
    "data": "Missing required field: method"
  }
}

Standard JSON-RPC error codes

Code	Meaning
`-32700`	Parse error — invalid JSON
`-32600`	Invalid request — missing required fields
`-32601`	Method not found
`-32602`	Invalid params
`-32603`	Internal error

MCP-specific error codes

Code	Meaning
`-32001`	Authentication failed — invalid or expired API key
`-32002`	Access denied — client not allowed to use this tool
`-32003`	Tool execution failed — upstream server error
`-32004`	Server unavailable — MCP server is not reachable

Available methods

tools/call

Execute a tool on a registered MCP server.

{
  "jsonrpc": "2.0",
  "id": "req-002",
  "method": "tools/call",
  "params": {
    "name": "generate_report",
    "arguments": {
      "client_id": "acme-retail",
      "report_type": "monthly_summary"
    }
  }
}

tools/list

List all available tools the API key has access to.

{
  "jsonrpc": "2.0",
  "id": "req-003",
  "method": "tools/list",
  "params": {}
}

ping

Health check endpoint.

{
  "jsonrpc": "2.0",
  "id": "req-004",
  "method": "ping",
  "params": {}
}

Batch requests

The gateway supports JSON-RPC batch requests. Send an array of request objects to execute multiple tool calls in a single HTTP request.

[
  {
    "jsonrpc": "2.0",
    "id": "req-005",
    "method": "tools/call",
    "params": {
      "name": "query_analytics",
      "arguments": { "client_id": "acme-retail", "metric": "page_views" }
    }
  },
  {
    "jsonrpc": "2.0",
    "id": "req-006",
    "method": "tools/call",
    "params": {
      "name": "query_analytics",
      "arguments": { "client_id": "acme-retail", "metric": "unique_visitors" }
    }
  }
]

Batch requests are executed concurrently. The response array maintains the same order as the request array.

Rate limiting

The gateway enforces rate limits per API key. Current limits:

Tier	Requests per minute	Concurrent connections
Standard	60	10
Enterprise	600	100

When rate limited, the gateway returns a -32603 error with a Retry-After header.

Rate limits are applied per API key, not per client. Create separate API keys for different services to isolate rate limits.

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