MCP Standards¶

Protocol Standards¶

The Model Context Protocol follows established standards and conventions to ensure interoperability and consistency.

Protocol Version¶

Current version: 2025-06-18

Version Format¶

MCP uses date-based versioning format: YYYY-MM-DD - Each revision represents the protocol state at that date - Breaking changes are indicated in the changelog - Implementations must support capability negotiation

Message Format¶

MCP uses JSON-RPC 2.0 specification.

Request Structure¶

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "tool_name",
    "arguments": {}
  },
  "id": 1
}

Response Structure¶

{
  "jsonrpc": "2.0",
  "result": {
    "content": []
  },
  "id": 1
}

Naming Conventions¶

Tools¶

• Format: snake_case
• Examples: get_user, create_ticket, fetch_data

Resources¶

• Format: URI scheme
• Examples: file://docs/readme, config://app/settings

Environment Variables¶

• Format: SCREAMING_SNAKE_CASE with role prefix
• Examples: MCP_GITHUB_TOKEN, MCP_SERVER_PORT

Error Codes¶

Standard JSON-RPC error codes plus MCP-specific ranges:

Data Types¶

Primitive Types¶

• string: UTF-8 text
• number: JSON number (float/int)
• boolean: true/false
• null: Null value

Complex Types¶

• object: JSON object with schema
• array: Ordered list of values

Content Types¶

MCP supports multiple content types in responses:

Transport Standards¶

HTTP¶

• Endpoint: /mcp
• Methods: POST only
• Content-Type: application/json
• Authentication: Bearer token in Authorization header

WebSocket¶

• Subprotocol: mcp.v1
• Ping/Pong: Every 30 seconds
• Message framing: Text frames with JSON

Compliance Requirements¶

All MCP implementations must: 1. Support JSON-RPC 2.0 2. Implement capability discovery 3. Provide error handling 4. Support graceful shutdown 5. Include health checks