{
  "title": "MCP Protocol Version Myths and Evidence",
  "schemaVersion": "1.0",
  "researchFreeze": "2026-08-26",
  "protocolRevision": "2026-07-28",
  "count": 35,
  "records": [
    {
      "id": "R7-MYTH001",
      "packageMythId": "MYTH001",
      "myth": "MCP has semantic versions like 1.0 and 2.0.",
      "correction": "Official protocol revisions are date strings; SDKs may use SemVer.",
      "packageSourceIds": [
        "S004",
        "S085"
      ],
      "sourceIds": [
        "S056",
        "S335"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH002",
      "packageMythId": "MYTH002",
      "myth": "MCP v2 always means `2026-07-28`.",
      "correction": "The phrase is informal and may refer to an SDK major release or the modern era.",
      "packageSourceIds": [
        "S004",
        "S052",
        "S085"
      ],
      "sourceIds": [
        "S056",
        "S252",
        "S335"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH003",
      "packageMythId": "MYTH003",
      "myth": "Every SDK release supports only one MCP version.",
      "correction": "Many SDK releases support several revisions.",
      "packageSourceIds": [
        "S051",
        "S053",
        "S056",
        "S059",
        "S066"
      ],
      "sourceIds": [
        "S138",
        "S253",
        "S166",
        "S325",
        "S331"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH004",
      "packageMythId": "MYTH004",
      "myth": "If two products say “MCP,” they are fully interoperable.",
      "correction": "Protocol, transport, auth, capabilities, extensions and host policy can differ.",
      "packageSourceIds": [
        "S004",
        "S073",
        "S074",
        "S075",
        "S076",
        "S077",
        "S078",
        "S079",
        "S080",
        "S081",
        "S082",
        "S083"
      ],
      "sourceIds": [
        "S056",
        "S145",
        "S259",
        "S140",
        "S090",
        "S141",
        "S265",
        "S269",
        "S144",
        "S274",
        "S284",
        "S297"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH005",
      "packageMythId": "MYTH005",
      "myth": "MCP guaranteed backward compatibility from launch.",
      "correction": "Compatibility is negotiated or implemented; breaking changes and removals occurred.",
      "packageSourceIds": [
        "S002",
        "S034",
        "S039",
        "S045"
      ],
      "sourceIds": [
        "S055",
        "S036",
        "S043",
        "S049"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH006",
      "packageMythId": "MYTH006",
      "myth": "`2024-11-05` is the public announcement date.",
      "correction": "The first named revision predates the November 25 announcement.",
      "packageSourceIds": [
        "S027",
        "S087"
      ],
      "sourceIds": [
        "S249",
        "S336"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH007",
      "packageMythId": "MYTH007",
      "myth": "Streamable HTTP existed at launch.",
      "correction": "It was introduced in `2025-03-26`.",
      "packageSourceIds": [
        "S029",
        "S036"
      ],
      "sourceIds": [
        "S027",
        "S038"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH008",
      "packageMythId": "MYTH008",
      "myth": "HTTP+SSE disappeared in March 2025.",
      "correction": "It was replaced as preferred but remained a legacy compatibility surface and was later deprecated.",
      "packageSourceIds": [
        "S002",
        "S034",
        "S036"
      ],
      "sourceIds": [
        "S055",
        "S036",
        "S038"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH009",
      "packageMythId": "MYTH009",
      "myth": "MCP always used OAuth.",
      "correction": "The launch revision had no core authorization framework.",
      "packageSourceIds": [
        "S027",
        "S037"
      ],
      "sourceIds": [
        "S249",
        "S037"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH010",
      "packageMythId": "MYTH010",
      "myth": "JSON-RPC batching was always unsupported.",
      "correction": "It was added in March 2025 and removed in June.",
      "packageSourceIds": [
        "S034",
        "S039"
      ],
      "sourceIds": [
        "S036",
        "S043"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH011",
      "packageMythId": "MYTH011",
      "myth": "Structured tool output existed at launch.",
      "correction": "It entered in June 2025.",
      "packageSourceIds": [
        "S030",
        "S039"
      ],
      "sourceIds": [
        "S028",
        "S043"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH012",
      "packageMythId": "MYTH012",
      "myth": "Elicitation existed at launch.",
      "correction": "It entered in June 2025.",
      "packageSourceIds": [
        "S043"
      ],
      "sourceIds": [
        "S046"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH013",
      "packageMythId": "MYTH013",
      "myth": "Tasks existed at launch.",
      "correction": "Experimental Tasks appeared in November 2025.",
      "packageSourceIds": [
        "S049"
      ],
      "sourceIds": [
        "S050"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH014",
      "packageMythId": "MYTH014",
      "myth": "Tasks are now part of the core.",
      "correction": "Current Tasks are an extension.",
      "packageSourceIds": [
        "S024",
        "S049"
      ],
      "sourceIds": [
        "S137",
        "S050"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH015",
      "packageMythId": "MYTH015",
      "myth": "The 2026 revision merely optimized HTTP.",
      "correction": "It changed lifecycle, sessions, server→client interaction, discovery, caching, routing and extensions.",
      "packageSourceIds": [
        "S002"
      ],
      "sourceIds": [
        "S055"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH016",
      "packageMythId": "MYTH016",
      "myth": "Stateless MCP cannot support long workflows.",
      "correction": "Applications maintain state through explicit handles, Tasks and external stores.",
      "packageSourceIds": [
        "S021",
        "S022",
        "S024"
      ],
      "sourceIds": [
        "S061",
        "S316",
        "S137"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH017",
      "packageMythId": "MYTH017",
      "myth": "`initialize` is still required in current MCP.",
      "correction": "It is a legacy-era method, not the modern lifecycle.",
      "packageSourceIds": [
        "S002",
        "S004"
      ],
      "sourceIds": [
        "S055",
        "S056"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH018",
      "packageMythId": "MYTH018",
      "myth": "`server/discover` is a new name for `initialize`.",
      "correction": "It advertises versions/capabilities but does not create a protocol session.",
      "packageSourceIds": [
        "S005",
        "S028"
      ],
      "sourceIds": [
        "S127",
        "S026"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH019",
      "packageMythId": "MYTH019",
      "myth": "Mcp-Session-Id is required for Streamable HTTP.",
      "correction": "It belongs to the legacy/session era and was removed from the current core.",
      "packageSourceIds": [
        "S002",
        "S009",
        "S047"
      ],
      "sourceIds": [
        "S055",
        "S131",
        "S321"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH020",
      "packageMythId": "MYTH020",
      "myth": "Modern MCP never uses SSE.",
      "correction": "Request-scoped SSE and subscription streams remain possible.",
      "packageSourceIds": [
        "S007",
        "S009"
      ],
      "sourceIds": [
        "S057",
        "S131"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH021",
      "packageMythId": "MYTH021",
      "myth": "resources/subscribe is the current resource subscription method.",
      "correction": "Current event delivery uses subscriptions/listen.",
      "packageSourceIds": [
        "S002",
        "S012"
      ],
      "sourceIds": [
        "S055",
        "S124"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH022",
      "packageMythId": "MYTH022",
      "myth": "Server-initiated requests are still the current interaction model.",
      "correction": "Modern MCP uses MRTR/input_required.",
      "packageSourceIds": [
        "S014",
        "S023"
      ],
      "sourceIds": [
        "S126",
        "S317"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH023",
      "packageMythId": "MYTH023",
      "myth": "Deprecated means removed.",
      "correction": "Deprecated features remain available during the policy window.",
      "packageSourceIds": [
        "S019",
        "S020"
      ],
      "sourceIds": [
        "S315",
        "S065"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH024",
      "packageMythId": "MYTH024",
      "myth": "Roots, Sampling and Logging stopped working on July 28.",
      "correction": "They were deprecated, not instantly removed.",
      "packageSourceIds": [
        "S002",
        "S019",
        "S020"
      ],
      "sourceIds": [
        "S055",
        "S315",
        "S065"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH025",
      "packageMythId": "MYTH025",
      "myth": "Tier 1 means every optional extension is implemented.",
      "correction": "Extensions are excluded from tier requirements.",
      "packageSourceIds": [
        "S050"
      ],
      "sourceIds": [
        "S073"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH026",
      "packageMythId": "MYTH026",
      "myth": "Tier 3 means an SDK is unsafe.",
      "correction": "Tier describes completeness/maintenance commitments, not a universal security verdict.",
      "packageSourceIds": [
        "S050"
      ],
      "sourceIds": [
        "S073"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH027",
      "packageMythId": "MYTH027",
      "myth": "A newer host always uses the newest protocol.",
      "correction": "Product and SDK defaults may prefer legacy or not disclose the selected revision.",
      "packageSourceIds": [
        "S073",
        "S074",
        "S075",
        "S076",
        "S077",
        "S078",
        "S079",
        "S080",
        "S081",
        "S082",
        "S083"
      ],
      "sourceIds": [
        "S145",
        "S259",
        "S140",
        "S090",
        "S141",
        "S265",
        "S269",
        "S144",
        "S274",
        "S284",
        "S297"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH028",
      "packageMythId": "MYTH028",
      "myth": "A current server cannot support old clients.",
      "correction": "Dual-era servers are documented by several official SDKs.",
      "packageSourceIds": [
        "S053",
        "S056",
        "S057",
        "S059",
        "S066"
      ],
      "sourceIds": [
        "S253",
        "S166",
        "S323",
        "S325",
        "S331"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH029",
      "packageMythId": "MYTH029",
      "myth": "A current client cannot support old servers.",
      "correction": "Probe-and-fallback is a documented compatibility strategy.",
      "packageSourceIds": [
        "S053",
        "S056",
        "S057",
        "S059",
        "S066"
      ],
      "sourceIds": [
        "S253",
        "S166",
        "S323",
        "S325",
        "S331"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH030",
      "packageMythId": "MYTH030",
      "myth": "A pinned modern client should silently fall back.",
      "correction": "Pinning is intended to fail rather than downgrade.",
      "packageSourceIds": [
        "S004",
        "S053",
        "S056"
      ],
      "sourceIds": [
        "S056",
        "S253",
        "S166"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH031",
      "packageMythId": "MYTH031",
      "myth": "One successful tool call proves complete compatibility.",
      "correction": "It proves only that one path worked.",
      "packageSourceIds": [
        "S004",
        "S011",
        "S012",
        "S013",
        "S014"
      ],
      "sourceIds": [
        "S056",
        "S123",
        "S124",
        "S125",
        "S126"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH032",
      "packageMythId": "MYTH032",
      "myth": "Protocol compatibility includes OAuth automatically.",
      "correction": "Authorization is a separate compatibility dimension.",
      "packageSourceIds": [
        "S004",
        "S010"
      ],
      "sourceIds": [
        "S056",
        "S133"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH033",
      "packageMythId": "MYTH033",
      "myth": "Protocol compatibility includes MCP Apps automatically.",
      "correction": "Apps are an extension and require separate support.",
      "packageSourceIds": [
        "S025"
      ],
      "sourceIds": [
        "S318"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH034",
      "packageMythId": "MYTH034",
      "myth": "Package downloads prove protocol adoption.",
      "correction": "Downloads do not measure unique active compatible deployments.",
      "packageSourceIds": [
        "S050",
        "S060",
        "S063",
        "S065",
        "S087"
      ],
      "sourceIds": [
        "S073",
        "S326",
        "S328",
        "S330",
        "S336"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    },
    {
      "id": "R7-MYTH035",
      "packageMythId": "MYTH035",
      "myth": "The latest specification makes all older documentation useless.",
      "correction": "Older versioned docs remain essential for legacy peers and history.",
      "packageSourceIds": [
        "S001",
        "S027",
        "S033",
        "S038",
        "S044"
      ],
      "sourceIds": [
        "S054",
        "S249",
        "S035",
        "S042",
        "S048"
      ],
      "sourceMappingStatus": "editorially-mapped-to-package-evidence"
    }
  ]
}