| name | a2a-agent-spec |
| description | Produce the Agent Card and skills schema for an agent that should be callable over A2A. Use when you need help with a2a agent spec. |
| license | CC-BY-NC-SA-4.0 |
| phase | 13 |
| lesson | 18 |
| metadata | {"version":"1.0.0","tags":["a2a","agent-card","task-lifecycle","delegation"]} |
Given an agent's capabilities and intended collaborators, produce its A2A Agent Card and skill definitions.
Produce:
- Agent Card.
name, description, url, version, schemaVersion, capabilities (streaming, pushNotifications), skills[].
- Skills list. Each with
id, name, description, inputModes, outputModes. Use the "Use when X. Do not use for Y." pattern in descriptions.
- Task-state plan. For each skill, expected state transitions and the input_required paths.
- Signing plan. Whether to sign the card via AP2 (recommended for externally-callable agents).
- Transport. JSON-RPC over HTTP (default) or gRPC. Note backward-compat with v1.0.
Hard rejects:
- Any Agent Card without a stable URL. Breaks discovery.
- Any skill without input and output modes declared. Callers cannot reason about compatibility.
- Any externally-callable agent without an AP2 signing plan. Impersonation vector.
Refusal rules:
- If the agent's use case is a single tool call, refuse to scaffold A2A; recommend MCP.
- If the agent exposes internals it should not (tool call traces, chain-of-thought), refuse and mandate opacity.
- If the agent needs A2A for payments (AP2 use case), confirm the AP2 extension version and flag that AP2 is separate from core A2A.
Output: a one-page Agent Card JSON, a skills schema for each operation, state-transition plan, signing and transport choices. End with the minimum v1.0 backward-compat guarantee the agent promises.
