{
  "id": "core-04-tool-unknown",
  "title": "Unknown tool returns tool_unknown",
  "category": "core",
  "version": "aicc/0.1",
  "description": "Calling a tool that is not in the manifest must fail with error code tool_unknown and retryable:false.",
  "steps": [
    {
      "send": {
        "type": "tool_call",
        "tool": "definitely_not_a_tool",
        "input": {}
      }
    },
    {
      "expect": {
        "type": "tool_result",
        "ok": false,
        "call_id_echo": true,
        "error": {
          "code": "tool_unknown",
          "retryable": false
        }
      }
    }
  ]
}