Agent Card
A JSON metadata document in the A2A protocol that describes an agent's capabilities, including its name, description, skills, input and output modalities, authentication methods and endpoint URL. It is used for automatic discovery and invocation of agents.
Core Facts
A2A introduces the concept of an Agent Card, where each Agent publishes a structured capability declaration document describing the task types it can handle, input/output formats, and authentication requirements.
An Agent Card is a standardized business card for agents in the A2A protocol, declaring capabilities, input/output schemas, authentication methods, and other information in JSON format, without exposing the internal model and tool implementations.
Timeline (last 90 days)
Agent-to-agent collaboration (A2A) means multiple agents directly exchange messages, dispatch subtasks, or verify each other's results, rather than routing all requests through a human intermediary.
The skills field of the Agent Card is mostly natural language descriptions plus a few examples, lacking formal constraints like JSON Schema on parameter types, required fields and value ranges, which is the main obstacle when wrapping A2A agents as MCP tools.
Starting with A2A v0.3, the Agent Card can carry a JWS cryptographic signature, allowing the recipient to verify that the card has not been tampered with and indeed comes from the claimed provider. But signatures address identity, not performance quality or content authenticity.
A2A's "compatible" label certifies limited things: the other party's identity is entirely self-declared, Agent Card signatures are optional rather than mandatory, there is no formal discovery registry, and the protocol is designed for opaque execution, so compliance certifies the conversation rather than the agent's behavior or conduct.
A2A achieves self-declaration and discovery of agent capabilities through the "Agent Card" mechanism, where each agent can expose a standardized .well-known/agent.json endpoint.
客户端通过向约定路径/.well-known/agent-card.json发起GET请求即可获取服务端的Agent Card信息
All Facts (10)
A2A introduces the concept of an Agent Card, where each Agent publishes a structured capability declaration document describing the task types it can handle, input/output formats, and authentication requirements.
80%VerifiedAn Agent Card is a standardized business card for agents in the A2A protocol, declaring capabilities, input/output schemas, authentication methods, and other information in JSON format, without exposing the internal model and tool implementations.
70%UnverifiedA2A协议通过Agent Card让每个Agent暴露能力清单，实现Agent之间零代码、零API契约的即插即用连接
90%UnverifiedA2A协议基于HTTP/SSE构建，引入了Agent Card概念，每个Agent发布描述自身能力的元数据卡片
90%UnverifiedAgent-to-agent collaboration (A2A) means multiple agents directly exchange messages, dispatch subtasks, or verify each other's results, rather than routing all requests through a human intermediary.
50%UnverifiedThe skills field of the Agent Card is mostly natural language descriptions plus a few examples, lacking formal constraints like JSON Schema on parameter types, required fields and value ranges, which is the main obstacle when wrapping A2A agents as MCP tools.
50%UnverifiedStarting with A2A v0.3, the Agent Card can carry a JWS cryptographic signature, allowing the recipient to verify that the card has not been tampered with and indeed comes from the claimed provider. But signatures address identity, not performance quality or content authenticity.
50%UnverifiedA2A's "compatible" label certifies limited things: the other party's identity is entirely self-declared, Agent Card signatures are optional rather than mandatory, there is no formal discovery registry, and the protocol is designed for opaque execution, so compliance certifies the conversation rather than the agent's behavior or conduct.
50%UnverifiedA2A achieves self-declaration and discovery of agent capabilities through the "Agent Card" mechanism, where each agent can expose a standardized .well-known/agent.json endpoint.
50%Unverified客户端通过向约定路径/.well-known/agent-card.json发起GET请求即可获取服务端的Agent Card信息
50%