Everything the Agent Card spec does not say out loud.
Practical A2A guides, reviewed against release 1.0.1, with a comparison of MCP revision 2026-07-28.
Articles are published in English; translations are shown when available.
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Unified agent architectures: A2A and MCP in practice under the AAIF
Discover how MCP and A2A now sit under the Linux Foundation's AAIF as a dual-layer architecture, pairing tool access with cross-framework agent discovery.
A2A x402 extension: enabling pay-per-call monetisation for AI agents
Learn how the A2A x402 extension lets an agent declare payment support in its Agent Card and charge for skills with on-chain stablecoin payments, using task states and message metadata.
A2A vs MCP: what changed in 2026
Compare A2A 1.0.1 and MCP 2026-07-28: discovery, stateless requests, task extensions, version negotiation, and Agent Card publishing.
How to create an agent-card.json (agent.json) file for A2A v1.0
Learn how to create the agent-card.json file, often called agent.json, for A2A v1.0, including required Agent Card fields, the well-known URL, response headers, and common mistakes.
Publishing an Agent Card from ADK, LangGraph, CrewAI or Semantic Kernel
Learn how to publish an A2A Agent Card from Google ADK, LangGraph, CrewAI, or Semantic Kernel by mapping framework concepts to standard discovery fields.
Agent Card validation errors explained, one by one
Diagnose every A2A v1.0 Agent Card validation error and warning, understand what triggers it, and apply the exact fix in validator check order.
What A2A v1.0 changed in the Agent Card
Learn how A2A v1.0 changes Agent Cards, from supportedInterfaces and securityRequirements to removed fields, with practical v0.3 migration examples.