{ "title": "MCP vs A2A FAQ", "schemaVersion": "1.0", "researchFreeze": "2026-08-26", "protocolRevision": "MCP 2026-07-28 / A2A 1.0", "mcpRevision": "2026-07-28", "a2aCompatibilityLine": "1.0", "a2aWebsiteSpecificationLabel": "1.0.0", "a2aRepositoryPatchTag": "v1.0.1", "a2aVersionSemantics": "A2A negotiates major.minor 1.0; patch tags identify specification releases and are not negotiated.", "schemaNote": "Visible answer dataset only. FAQPage JSON-LD is intentionally not emitted, and no FAQ rich-result eligibility is claimed.", "count": 50, "records": [ { "id": "R8-FAQ001", "packageFaqId": "FAQ001", "question": "What is MCP?", "answer": "MCP is a protocol through which AI applications discover and use server-exposed tools, resources, prompts and extensions.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ002", "packageFaqId": "FAQ002", "question": "What is A2A?", "answer": "A2A is a protocol for independently implemented agents to discover one another, exchange Messages, delegate work, track Tasks and return Artifacts.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ003", "packageFaqId": "FAQ003", "question": "What is the main difference between MCP and A2A?", "answer": "MCP usually governs access to capabilities; A2A governs collaboration and delegation between agents.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ004", "packageFaqId": "FAQ004", "question": "Does A2A replace MCP?", "answer": "No. Official A2A documentation presents them as complementary.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ005", "packageFaqId": "FAQ005", "question": "Can a system use both?", "answer": "Yes. A2A can connect agents while each agent uses MCP for tools and data.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ006", "packageFaqId": "FAQ006", "question": "Is an MCP server an agent?", "answer": "Not inherently. It may be deterministic, rule-based or a wrapper around an API.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ007", "packageFaqId": "FAQ007", "question": "Is an A2A server an agent?", "answer": "Yes in the protocol role sense: it is the remote agent application accepting Messages and Tasks.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ008", "packageFaqId": "FAQ008", "question": "What is an MCP tool?", "answer": "A named, schema-described operation exposed by an MCP server.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ009", "packageFaqId": "FAQ009", "question": "What is an A2A skill?", "answer": "A descriptive ability advertised in an Agent Card; it may be fulfilled through many internal tools or workflows.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ010", "packageFaqId": "FAQ010", "question": "Are tools and skills equivalent?", "answer": "No. Tools are invocation-shaped; skills are broader advertised abilities.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ011", "packageFaqId": "FAQ011", "question": "What is an Agent Card?", "answer": "A discovery document describing an A2A agent’s identity, interfaces, versions, security and skills.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ012", "packageFaqId": "FAQ012", "question": "What is server/discover?", "answer": "`server/discover` is required for MCP 2026-07-28 servers. A client may skip that preflight call, invoke another RPC directly, and handle an unsupported-version error.", "packageAnswer": "An optional MCP method that reports a server’s supported versions and capabilities.", "packageSourceIds": [ "S044" ], "sourceIds": [ "S127" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence", "editorialCorrection": "Current primary-source publication correction applied." }, { "id": "R8-FAQ013", "packageFaqId": "FAQ013", "question": "Is server/discover the same as an Agent Card?", "answer": "No. It is live server capability discovery, not a complete agent identity and skill document.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ014", "packageFaqId": "FAQ014", "question": "How are public A2A agents discovered?", "answer": "Commonly through /.well-known/agent-card.json, direct configuration or registries.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ015", "packageFaqId": "FAQ015", "question": "How are MCP tools discovered?", "answer": "Through server/discover and tools/list, subject to host policy and protocol version.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ016", "packageFaqId": "FAQ016", "question": "What is an MCP Task?", "answer": "An optional extension result that gives a durable handle for a long-running MCP request.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ017", "packageFaqId": "FAQ017", "question": "What is an A2A Task?", "answer": "The core tracked unit of agent work, with status, history and Artifacts.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ018", "packageFaqId": "FAQ018", "question": "Are MCP Tasks and A2A Tasks compatible?", "answer": "No. They use different protocols, states and operations.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ019", "packageFaqId": "FAQ019", "question": "Can A2A return without creating a Task?", "answer": "Yes. A simple interaction may return a direct Message.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ020", "packageFaqId": "FAQ020", "question": "Which protocol has task listing?", "answer": "A2A v1.0 has List Tasks; current MCP Tasks intentionally omits a general tasks/list.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ021", "packageFaqId": "FAQ021", "question": "Which protocol supports push notifications?", "answer": "A2A defines push-notification configuration in its core operations; MCP is developing broader event mechanisms and uses subscriptions/notifications for selected features.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ022", "packageFaqId": "FAQ022", "question": "Which protocol supports local stdio servers?", "answer": "MCP.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ023", "packageFaqId": "FAQ023", "question": "Which protocol supports gRPC?", "answer": "A2A v1.0 defines gRPC as a core binding.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ024", "packageFaqId": "FAQ024", "question": "Do both use JSON-RPC?", "answer": "MCP is JSON-RPC based; A2A offers a JSON-RPC binding alongside HTTP+JSON and gRPC.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ025", "packageFaqId": "FAQ025", "question": "Is MCP stateless?", "answer": "The current 2026-07-28 core is stateless at the protocol request layer.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ026", "packageFaqId": "FAQ026", "question": "Is A2A stateless?", "answer": "Its v1.0 architecture is web-aligned and stateless at the service layer while Task and context state are explicit.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ027", "packageFaqId": "FAQ027", "question": "Who owns reasoning in MCP?", "answer": "Usually the host/model, although a server can perform complex internal work.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ028", "packageFaqId": "FAQ028", "question": "Who owns reasoning in A2A?", "answer": "The remote agent may own its plan and execution strategy.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ029", "packageFaqId": "FAQ029", "question": "Can an A2A agent use MCP tools?", "answer": "Yes; this is the canonical complementary architecture.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ030", "packageFaqId": "FAQ030", "question": "Can an MCP server call an A2A agent?", "answer": "Yes as an implementation choice, though MCP does not standardize that internal delegation.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ031", "packageFaqId": "FAQ031", "question": "Should I expose an agent as one MCP tool?", "answer": "Only when a bounded invocation contract is sufficient. Use A2A when task lifecycle, skill discovery and agent discretion matter.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ032", "packageFaqId": "FAQ032", "question": "Should I expose a deterministic API as an A2A agent?", "answer": "Usually not; direct APIs or MCP are simpler when no independent agent behavior is needed.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ033", "packageFaqId": "FAQ033", "question": "How does authorization differ?", "answer": "MCP defines a detailed OAuth resource-server profile; A2A declares web security schemes in Agent Cards and leaves credential acquisition out of protocol messages.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ034", "packageFaqId": "FAQ034", "question": "Do signed Agent Cards make agents trustworthy?", "answer": "They can verify integrity and signer identity, not competence, safety or authorization.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ035", "packageFaqId": "FAQ035", "question": "What are A2A Artifacts?", "answer": "Deliverables produced by a Task, composed of content Parts and capable of incremental updates.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ036", "packageFaqId": "FAQ036", "question": "Are A2A Artifacts MCP resources?", "answer": "No, although a bridge can store or expose an Artifact as a resource.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ037", "packageFaqId": "FAQ037", "question": "What is contextId in A2A?", "answer": "An opaque identifier that groups related A2A Messages and Tasks. An agent may generate it when absent and may accept a client-provided value; authorization must not rely on the identifier alone.", "packageAnswer": "A server-generated identifier grouping related Messages and Tasks.", "packageSourceIds": [ "S003" ], "sourceIds": [ "S339" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence", "editorialCorrection": "Current primary-source publication correction applied." }, { "id": "R8-FAQ038", "packageFaqId": "FAQ038", "question": "Does MCP have contextId?", "answer": "No equivalent core field; host context and explicit application handles are separate.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ039", "packageFaqId": "FAQ039", "question": "Which protocol is better for multi-agent systems?", "answer": "A2A is designed for inter-agent communication; MCP remains useful inside each agent.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ040", "packageFaqId": "FAQ040", "question": "Which protocol is better for database access?", "answer": "MCP, unless the remote component is a database-specialist agent that owns a broader task.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ041", "packageFaqId": "FAQ041", "question": "Which protocol is better for incident response?", "answer": "Often both: A2A between specialist agents and MCP for logs, metrics and remediation tools.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ042", "packageFaqId": "FAQ042", "question": "Which protocol is more secure?", "answer": "Neither universally. Their threat models differ, and deployment authority determines risk.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ043", "packageFaqId": "FAQ043", "question": "Can a host use MCP without an LLM?", "answer": "Yes.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ044", "packageFaqId": "FAQ044", "question": "Can an A2A client be non-agent software?", "answer": "Yes; the client role can be an application acting on behalf of a user or system.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ045", "packageFaqId": "FAQ045", "question": "Is A2A an agent framework?", "answer": "No. It is a communication protocol between agents built with frameworks.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ046", "packageFaqId": "FAQ046", "question": "Is MCP an agent framework?", "answer": "No. It is an integration protocol.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ047", "packageFaqId": "FAQ047", "question": "Who governs MCP?", "answer": "MCP maintainers and its public governance process under AAIF hosting.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ048", "packageFaqId": "FAQ048", "question": "Who governs A2A?", "answer": "An eight-seat Technical Steering Committee under its project governance and current AAIF hosting.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ049", "packageFaqId": "FAQ049", "question": "Are MCP and A2A official internet standards?", "answer": "They are open protocols, not IETF, W3C or ISO standards as of the verification date.", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence" }, { "id": "R8-FAQ050", "packageFaqId": "FAQ050", "question": "What versions are current?", "answer": "This comparison freezes MCP at `2026-07-28` and A2A at the stable `1.0` compatibility line. The A2A website labels the released specification `1.0.0`, while the repository lists a `v1.0.1` patch tag. A2A wire negotiation uses major.minor `1.0`; patch tags are not sent or compared for compatibility.", "packageAnswer": "MCP 2026-07-28 is current; A2A is on the stable 1.0 line with a v1.0.1 patch release. Live-check before publication.", "packageSourceIds": [ "S003", "S015", "S038" ], "sourceIds": [ "S339", "S351", "S054" ], "sourceMappingStatus": "editorially-mapped-to-package-evidence", "editorialCorrection": "Current primary-source publication correction applied." } ] }