Agent Card
An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes. In the agentic web (Step 1, Discover), also known as A2A Agent Card, agent-card.json, it is implemented or referenced by Agent2Agent Protocol (A2A).
Discover An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes. A client agent fetches a card before talking to a server so it can decide whether to use it and how to structure requests. The recommended discovery mechanism is a well-known URI, /.well-known/agent-card.json, following RFC 8615, though curated registries and direct configuration are also defined discovery strategies. Cards can also be served behind authentication when they carry sensitive detail, using an "authenticated extended" variant. This is A2A's own discovery object; it is distinct from an MCP server card, which describes an MCP server rather than an A2A agent. Used by: a2a.
Overview
An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes. In the agentic web (Step 1, Discover), also known as A2A Agent Card, agent-card.json, it is implemented or referenced by Agent2Agent Protocol (A2A).
Instances
- Agent Community / Open Agent Registry (AID) · Observed 2026-10-23 · registry / facilitator
- Mnemom Cryptographic Agent Trust Service · Observed 2026-10-23 · trust authority
- Neuronto Agentic Web Index · Observed 2026-10-23 · registry / facilitator
- IBM BeeAI Multi-Agent Runtime · Observed 2026-08-29 · autonomous agent
- CopilotKit · Observed 2026-08-14 · client / harness
- 8004.org / ERC-8004 Trustless Agents Registry · Observed 2026-08-13 · registry / facilitator
- Google Agent Development Kit (ADK) · Observed 2026-07-31 · client / harness
- AGNTCY Agent Directory Service (Linux Foundation) · Observed 2026-07-23 · registry / facilitator
- Nevermined x402 Facilitator and Metering Clearinghouse · Observed 2026-07-23 · registry / facilitator
- GoDaddy Agent Name Service (ANS) Authority · Observed 2026-07-15 · trust authority
- Infoblox DNS-AID Registry (Linux Foundation) · Observed 2026-07-15 · registry / facilitator
- OpenA2A Agent Authorization Protocol (AAP) Authority · Observed 2026-07-02 · trust authority
See also
References
- https://a2a-protocol.org/v1.0.0/topics/agent-discovery/ (2026-09-05) VERIFIED
Frequently asked questions
- What is Agent Card?
- An Agent Card is a JSON document that an A2A server publishes to describe itself to other agents: its identity (name, description, provider), its service endpoint URL, the A2A capabilities it supports (streaming, push notifications), its authentication schemes, and the skills it offers, each with an id, description, and input/output modes. In the agentic web (Step 1, Discover), also known as A2A Agent Card, agent-card.json, it is implemented or referenced by Agent2Agent Protocol (A2A).
- Which agentic web standards use Agent Card?
- Agent Card is used or referenced by Agent2Agent Protocol (A2A). See https://agenticweb.wiki/terms/agent-card/ for sourced definitions and verified implementations.
- How is Agent Card verified on agenticweb.wiki?
- The Agent Card record cites 1 primary specification or implementation source and was last verified on 2026-10-30.