MCP / A2A Interoperability Kit

Reference architecture for agent interoperability using Model Context Protocol (MCP)-style tool servers and agent-to-agent (A2A) messaging patterns.

Demonstrates how tools and agents should expose typed contracts across process boundaries.

Architecture Focus

• MCP-style tool server surface (list/call tools)
• A2A task delegation between agents
• Schema validation for tool inputs/outputs
• Capability discovery
• Isolation boundaries for untrusted tools

High-Level Architecture

flowchart TB
  HostAgent --> MCPClient
  MCPClient --> MCPServer
  MCPServer --> Tools
  HostAgent --> A2AClient
  A2AClient --> PeerAgent
  PeerAgent --> MCPServer

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Key Capabilities

Area	What it shows
MCP server	Tool catalog + invoke endpoints
MCP client	Discovery and typed invocation
A2A	Delegate a task payload to a peer agent
Contracts	JSON-schema-like pydantic models

Technology Stack

• Python 3.11+
• FastAPI
• Pydantic
• httpx
• pytest

Setup

python -m venv .venv
source .venv/bin/activate  # Windows: .venv\Scripts\activate
pip install -r requirements.txt
pytest
uvicorn src.mcp_server.app:app --port 8081 --reload

Example Usage

from src.mcp_client.client import McpClient

client = McpClient("http://127.0.0.1:8081")
tools = client.list_tools()
result = client.call_tool("echo", {"text": "hello agents"})

Security Considerations

• Authenticate server-to-server calls in real deployments
• Constrain tool side effects and network egress
• Validate all tool arguments before execution
• Treat peer-agent output as untrusted

Known Limitations

• Simplified HTTP stand-in for MCP transport (stdio/SSE not fully implemented)
• A2A message model is intentionally minimal

License

MIT