mcp-skill

Recipe: mcp-skill

Demonstrates the MCP-to-ARCP bridge pattern — exposing an ARCP skill as an MCP tool that any MCP-compatible host (Claude Desktop, Cursor, etc.) can call (RFC §16).

MCP Host (simulated)
  │
  │  JSON-RPC 2.0 (stdio)
  ▼
McpBridge
  ├── initialize        → serverInfo + capabilities
  ├── tools/list        → [{ name: "research", inputSchema: {...} }]
  └── tools/call research
        │
        │  ARCP
        ▼
      ARCPRuntime
        └── planner@1.0.0
              ├── job.submit        → job.accepted
              ├── [agent simulated] → job.completed(result)
              └── Ack

The recipe shows three bridge patterns from RFC §16:

1. MCP capability handshake — the bridge responds to initialize with its server info and declares tools capability.
2. Skill-as-tool — tools/list translates the ARCP skill manifest (skills/research/SKILL.md) into an MCP Tool object with a JSON Schema inputSchema.
3. End-to-end tools/call — tools/call research submits an ARCP job.submit, awaits job.accepted, simulates the agent result, sends job.completed, and wraps the result in an MCP TextContent block.

Because the recipe is self-contained (no real stdin or MCP client required), Main.kt replays four canned JSON-RPC 2.0 messages — initialize, notifications/initialized, tools/list, and tools/call research — against the bridge to show the full flow.

API keys

No external services are used — everything runs in-process with MemoryTransport.

Running

export JAVA_HOME=/opt/homebrew/opt/openjdk@21
./gradlew :recipes:runMcpSkill

What to look for

• [bridge] connected sessionId=... — ARCP session established.
• [host ] ← {"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05",...}} — MCP initialize handshake completed.
• [host ] ← {"jsonrpc":"2.0","id":2,"result":{"tools":[{"name":"research",...}]}} — tools/list returned the research skill.
• [bridge] tools/call research query="advances in ..." — bridge received the tools/call and is dispatching to ARCP.
• [bridge] job accepted jobId=... — runtime accepted the job.
• [bridge] agent result summary=... — simulated agent produced a result.
• [bridge] job completed ackReceived=true — runtime Acked the completion.
• [host ] ← {"jsonrpc":"2.0","id":3,"result":{"content":[{"type":"text","text":...}]}} — final MCP tool result returned to the host.