Expose mcp-agent apps (MCPApp) as MCP servers

[saqadri]

Summary

This PR adds server capabilities to mcp-agent applications, allowing workflows and agents to be exposed as API endpoints via a new server abstraction. The motivation for this is to enable mcp-agent apps to be easily integrated into any MCP-compatible client application.

mcp_agent_as_server3.mov

It introduces three key components:

1. create_mcp_server_for_app function - Creates an MCP server for any MCPApp instance, exposing workflows and agents as tools
2. FastMCPApp class - Extends MCPApp with declarative agent creation using decorators
3. Server endpoint architecture - Provides standardized patterns for workflow and agent interactions

Key Features

Server Architecture

• Workflow-related endpoints:

  • workflows/list - Lists available workflows with detailed information
  • workflows/run - Schedules workflow execution and returns a workflow ID
  • workflows/get_status - Retrieves current workflow status
  • workflows/cancel - Terminates a running workflow
  • Per-workflow endpoints: workflows/{workflow_name}/run for direct access

• Agent-related endpoints:

  • agents/list - Lists available agents with detailed information
  • agents/generate, agents/generate_str, agents/generate_structured - Generic agent interaction
  • Per-agent endpoints: agents/{agent_name}/generate* for direct access

Declarative Agent Creation

FastMCPApp introduces decorators for defining various agent types:

• @app.agent - Basic agent configuration
• @app.parallel - Fan-out/fan-in workflow agents
• @app.orchestrator - Coordinating workflow agent
• @app.router - Request routing workflow agent
• @app.evaluator_optimizer - Quality assurance workflow agent

Current Limitations

• Only works with asyncio (Temporal support needed)
• Tracing and observability need improvement
• Some edge cases in workflow tracking need handling

Future Work

• Integration with Temporal for production-grade workflow execution
• Enhanced logging and tracing throughout the server lifecycle
• Comprehensive error handling and recovery mechanisms
• More structured schema definitions for endpoint inputs/outputs

[saqadri]

Feel free to comment on the PR, will track it. Merging into parent feature branch to continue building on top of this