{ "title": "MCP vs A2A — Master Comparison", "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.", "count": 28, "records": [ { "Property": "Full name", "MCP": "Model Context Protocol", "A2A": "Agent2Agent Protocol", "id": "R8-CMP01", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Primary boundary", "MCP": "AI application or agent to capability provider", "A2A": "Client agent to remote agent", "id": "R8-CMP02", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Typical remote component", "MCP": "Focused server wrapping tools, data, APIs or local code", "A2A": "Opaque agent application that may plan and use its own tools", "id": "R8-CMP03", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Caller intent", "MCP": "Invoke or retrieve a bounded capability", "A2A": "Delegate a goal, request or collaborative unit of work", "id": "R8-CMP04", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Core discovery", "MCP": "server/discover plus tools/resources/prompts list methods", "A2A": "Agent Card, usually at /.well-known/agent-card.json or through registry/configuration", "id": "R8-CMP05", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Capability unit", "MCP": "Tool, resource, prompt or extension", "A2A": "Agent skill advertised in an Agent Card", "id": "R8-CMP06", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Execution abstraction", "MCP": "tools/call or other concrete protocol request", "A2A": "Message that may yield direct Message or durable Task", "id": "R8-CMP07", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Long-running work", "MCP": "Optional Tasks extension", "A2A": "Task is a core protocol object", "id": "R8-CMP08", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Immediate response", "MCP": "Synchronous result or input_required/task result where supported", "A2A": "Direct Message or Task", "id": "R8-CMP09", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Durable output", "MCP": "Tool/resource result; task result under extension", "A2A": "Artifacts attached to a Task", "id": "R8-CMP10", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Multi-turn grouping", "MCP": "Host/application conversation; explicit handles; MRTR", "A2A": "contextId and Task history", "id": "R8-CMP11", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Reasoning ownership", "MCP": "Usually host/model; server may perform internal logic", "A2A": "Remote agent may own planning and reasoning", "id": "R8-CMP12", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Implementation opacity", "MCP": "Server internals can be hidden but interface is capability-shaped", "A2A": "Opaque execution is an explicit design principle", "id": "R8-CMP13", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Local deployment", "MCP": "Common through stdio", "A2A": "Can connect local agents, but A2A does not define MCP's standardized subprocess/stdio binding.", "id": "R8-CMP14", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "editorialCorrection": "Removed the implication that A2A is inherently remote." }, { "Property": "Network bindings", "MCP": "stdio and Streamable HTTP in current core", "A2A": "JSON-RPC, HTTP+JSON/REST and gRPC; custom bindings permitted", "id": "R8-CMP15", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Streaming", "MCP": "Request-scoped SSE, subscriptions/listen and progress patterns", "A2A": "SSE streaming, task subscription, polling and push notifications", "id": "R8-CMP16", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Push/webhooks", "MCP": "Roadmap/extension territory, not a general core webhook model", "A2A": "Core push-notification configuration operations", "id": "R8-CMP17", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Identity advertisement", "MCP": "Server info and capabilities; remote OAuth metadata", "A2A": "Agent Card provider, interfaces, security schemes and optional signatures", "id": "R8-CMP18", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Authorization model", "MCP": "Detailed OAuth resource-server profile for remote MCP", "A2A": "Web-security schemes declared in Agent Card; credentials out of message body", "id": "R8-CMP19", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Version form", "MCP": "Date-based core revisions such as 2026-07-28", "A2A": "Major.minor compatibility such as 1.0; patch tags identify specification releases but are not negotiated.", "id": "R8-CMP20", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ], "editorialCorrection": "Qualified A2A wire-version semantics." }, { "Property": "Core data model", "MCP": "JSON-RPC types and JSON Schema-described capabilities", "A2A": "Normative Protocol Buffers data model mapped across bindings", "id": "R8-CMP21", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Model required", "MCP": "No", "A2A": "No, although remote party is defined as an agent application", "id": "R8-CMP22", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Agent required", "MCP": "No", "A2A": "Yes in the protocol role sense", "id": "R8-CMP23", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Can wrap APIs", "MCP": "Commonly", "A2A": "An agent can use APIs internally, often through MCP or framework tools", "id": "R8-CMP24", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Can be used together", "MCP": "Yes: MCP inside agents and A2A between agents", "A2A": "Yes: A2A delegates to agents that use MCP", "id": "R8-CMP25", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Best fit", "MCP": "Reusable bounded tools, data and interaction surfaces", "A2A": "Cross-agent delegation, collaboration and long-running agent work", "id": "R8-CMP26", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Weak fit", "MCP": "Treating every autonomous agent as one oversized tool", "A2A": "Using a remote agent for a deterministic low-level function", "id": "R8-CMP27", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] }, { "Property": "Governance in August 2026", "MCP": "AAIF founding project with MCP-specific maintainers and SEPs", "A2A": "AAIF hosted project with its own eight-seat TSC and repositories", "id": "R8-CMP28", "packageSourceIds": [ "S003", "S004", "S038" ], "sourceIds": [ "S339", "S340", "S054" ] } ] }