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ARC Protocol Specification

ARC (Agent Remote Communication) is a stateless, lightweight remote procedure call (RPC) protocol for agent communications in multi-agent systems (MAS) with workflow tracing capabilities, quantum-safe hybrid TLS encryption, and single-endpoint multi-agent routing.

Specification Files​

Primary Specification​

arc-openrpc.json - OpenRPC format

  • Primary RPC specification
  • Method definitions
  • Type schemas
  • Error codes

Tooling Compatibility​

arc-openapi.yaml - OpenAPI 3.0 format

  • Source for generating OpenRPC
  • Used for tooling compatibility
  • TypeScript type generation

Full Specification​

View the complete specification:

ARC Specification Document

Core Protocol Features​

Stateless RPC Design​

  • No session state on server
  • Each request is independent
  • Client manages chatId and taskId

Single Endpoint Architecture​

  • All agents accessible via /arc
  • Routing via targetAgent field
  • Simplified deployment and discovery

Workflow Tracing​

  • traceId propagates across agent calls
  • End-to-end observability
  • Integration with tracing systems

Quantum-Safe Security​

  • Hybrid TLS: X25519 + Kyber-768
  • FIPS 203 ML-KEM compliant
  • Future-proof encryption

Method Categories​

Task Methods​

Asynchronous operations:

  • task.create
  • task.send
  • task.info
  • task.cancel
  • task.subscribe
  • task.notification

Chat Methods​

Real-time communication:

  • chat.start
  • chat.message
  • chat.end

Request Structure​

{
  "method": "chat.start",
  "params": {
    "requestAgent": "client-123",
    "targetAgent": "finance-agent",
    "traceId": "trace-abc",
    "initialMessage": {
      "role": "user",
      "parts": [{"type": "text", "content": "Help with invoice"}]
    }
  }
}

Response Structure​

{
  "result": {
    "type": "chat",
    "chat": {
      "chatId": "chat-xyz",
      "status": "ACTIVE",
      "message": {
        "role": "agent",
        "parts": [{"type": "text", "content": "I can help with that"}]
      }
    }
  }
}

Error Handling​

ARC uses standard RPC error codes (borrowed from JSON-RPC convention):

  • -32600 - Invalid Request
  • -32601 - Method not found
  • -32602 - Invalid params
  • -32603 - Internal error
  • -42001 - Agent not found
  • -42002 - Authentication failed
  • -42003 - Task not found
  • -42004 - Task processing error

Schema Usage​

Generate TypeScript Types​

npm run generate:types

Generate OpenRPC from OpenAPI​

npm run generate:openrpc

Validate Schema​

npm run validate