Phase 3: Evaluate and implement A2A protocol support

[bokelley]

Overview

Evaluate the A2A (Agent-to-Agent) protocol and implement support if it proves valuable for the signals agent.

Background

The AdCP specification supports multiple protocols (MCP, A2A, REST). We currently support MCP. This issue tracks the evaluation and potential implementation of A2A support.

Tasks

Evaluation Phase

• Research A2A Python SDK capabilities and requirements
• Create proof-of-concept A2A server wrapper
• Assess integration complexity and maintenance burden
• Determine if A2A provides significant value over MCP

Implementation Phase (if proceeding)

• Install a2a-sdk (minimal installation, no database features needed)
• Create A2A server implementation alongside MCP
• Map signals tasks to A2A methods
• Handle protocol-specific request/response translation
• Enable running both MCP and A2A servers concurrently

Protocol Abstraction

• Create common interface for task implementation
• Allow tasks to be protocol-agnostic
• Prepare for future REST API support

Architecture

┌─────────────┐     ┌─────────────┐
│  MCP Client │     │  A2A Client │
└──────┬──────┘     └──────┬──────┘
       │                   │
┌──────▼──────┐     ┌──────▼──────┐
│ MCP Server  │     │ A2A Server  │
└──────┬──────┘     └──────┬──────┘
       │                   │
       └─────────┬─────────┘
                 │
         ┌───────▼────────┐
         │  Core Logic    │
         │  - Discover    │
         │  - Activate    │
         │  - Adapters    │
         └────────────────┘

Considerations

• A2A SDK includes features we don't need (database integrations, state management)
• Limited documentation available for A2A
• Need to ensure value proposition before committing to maintenance

Success Criteria

• Clear understanding of A2A benefits vs complexity
• If implemented: Both MCP and A2A protocols work seamlessly
• Shared business logic between protocols
• No degradation of existing MCP functionality

References

• A2A Python SDK: https://github.com/a2aproject/a2a-python
• AdCP PR Fix adapter import error by removing test_mode logic #19: Multi-protocol support