{
  "title": "Official MCP SDK Compatibility Matrix",
  "schemaVersion": "1.0",
  "researchFreeze": "2026-08-26",
  "protocolRevision": "2026-07-28",
  "freshnessNote": "SDK tiers, package lines, defaults, and protocol coverage are live-check fields verified on 2026-08-26.",
  "count": 10,
  "records": [
    {
      "id": "R7-SDK01",
      "language": "TypeScript",
      "officialTier": "Tier 1",
      "currentStableLine": "v2 packages",
      "highestDocumentedProtocol": "2026-07-28",
      "olderRevisions": "Both legacy and modern eras; legacy set includes all prior released revisions",
      "autoDetectionFallback": "Available through versionNegotiation mode=auto; default hand-built client remains legacy unless opted in",
      "serverDualEraSupport": "createMcpHandler/serveStdio can serve both",
      "confidence": "VERIFIED",
      "packageSourceIds": [
        "S051",
        "S052",
        "S053",
        "S054",
        "S055"
      ],
      "sourceIds": [
        "S138",
        "S252",
        "S253",
        "S168",
        "S322"
      ],
      "liveCheckNote": "Exact package versions and defaults can change.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 1",
        "liveCheckNote": "Exact package versions and defaults can change."
      }
    },
    {
      "id": "R7-SDK02",
      "language": "Python",
      "officialTier": "Tier 1",
      "currentStableLine": "2.x",
      "highestDocumentedProtocol": "2026-07-28",
      "olderRevisions": "Legacy handshake revisions through 2025-11-25",
      "autoDetectionFallback": "Default auto probe, then initialize fallback",
      "serverDualEraSupport": "One streamable_http_app and stdio server serves both",
      "confidence": "VERIFIED",
      "packageSourceIds": [
        "S051",
        "S056",
        "S057",
        "S058"
      ],
      "sourceIds": [
        "S138",
        "S166",
        "S323",
        "S324"
      ],
      "liveCheckNote": "Exact PyPI version must be checked at publication.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 1",
        "liveCheckNote": "Exact PyPI version must be checked at publication."
      }
    },
    {
      "id": "R7-SDK03",
      "language": "C#",
      "officialTier": "Tier 1",
      "currentStableLine": "2.x/current official line",
      "highestDocumentedProtocol": "2026-07-28 per GA/Tier 1 readiness",
      "olderRevisions": "Tier 1 conformance and compatibility depend on release line",
      "autoDetectionFallback": "SDK-specific; verify current docs",
      "serverDualEraSupport": "Verify current release documentation",
      "confidence": "STRONGLY_SUPPORTED",
      "packageSourceIds": [
        "S015",
        "S051",
        "S061",
        "S062"
      ],
      "sourceIds": [
        "S058",
        "S138",
        "S078",
        "S327"
      ],
      "liveCheckNote": "Exact NuGet package-to-revision matrix requires live check.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 1",
        "liveCheckNote": "Exact NuGet package-to-revision matrix requires live check."
      }
    },
    {
      "id": "R7-SDK04",
      "language": "Go",
      "officialTier": "Tier 1",
      "currentStableLine": "v1.7.0+",
      "highestDocumentedProtocol": "2026-07-28",
      "olderRevisions": "2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05",
      "autoDetectionFallback": "Current SDK supports modern and legacy negotiation/fallback",
      "serverDualEraSupport": "Yes; stateless HTTP option is explicit in current line",
      "confidence": "VERIFIED",
      "packageSourceIds": [
        "S051",
        "S059",
        "S060"
      ],
      "sourceIds": [
        "S138",
        "S325",
        "S326"
      ],
      "liveCheckNote": "Use the exact compatibility table for the deployed SDK version.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 1",
        "liveCheckNote": "Use the exact compatibility table for the deployed SDK version."
      }
    },
    {
      "id": "R7-SDK05",
      "language": "Java",
      "officialTier": "Tier 2",
      "currentStableLine": "2.x",
      "highestDocumentedProtocol": "2025-11-25 in reviewed stable release documentation",
      "olderRevisions": "Earlier 2025-era revisions",
      "autoDetectionFallback": "2026 server/discover support not established in reviewed stable line",
      "serverDualEraSupport": "Not established",
      "confidence": "STRONGLY_SUPPORTED",
      "packageSourceIds": [
        "S051",
        "S063",
        "S064"
      ],
      "sourceIds": [
        "S138",
        "S328",
        "S329"
      ],
      "liveCheckNote": "Open implementation work may have landed after verification.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 2",
        "liveCheckNote": "Open implementation work may have landed after verification."
      }
    },
    {
      "id": "R7-SDK06",
      "language": "Rust",
      "officialTier": "Tier 1",
      "currentStableLine": "rmcp 3.x",
      "highestDocumentedProtocol": "2026-07-28",
      "olderRevisions": "Legacy compatibility documented by release notes/implementation",
      "autoDetectionFallback": "SDK-specific modern/legacy behavior",
      "serverDualEraSupport": "Supported according to release implementation; verify topology",
      "confidence": "STRONGLY_SUPPORTED",
      "packageSourceIds": [
        "S051",
        "S065"
      ],
      "sourceIds": [
        "S138",
        "S330"
      ],
      "liveCheckNote": "Official SDK documentation checked on 2026-08-26 lists Rust as Tier 1; crate versions and protocol behavior still require a live check.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 2",
        "liveCheckNote": "Crate versions and tier may change."
      },
      "editorialCorrection": "Updated the package Tier 2 snapshot to the Tier 1 assignment on the current official SDK page; the raw value remains in packageSnapshot."
    },
    {
      "id": "R7-SDK07",
      "language": "Ruby",
      "officialTier": "Tier 2",
      "currentStableLine": "1.x",
      "highestDocumentedProtocol": "2026-07-28",
      "olderRevisions": "All five released revisions documented",
      "autoDetectionFallback": "server/discover probe with initialize fallback",
      "serverDualEraSupport": "Official transports serve both eras",
      "confidence": "VERIFIED",
      "packageSourceIds": [
        "S051",
        "S066",
        "S067",
        "S068"
      ],
      "sourceIds": [
        "S138",
        "S331",
        "S084",
        "S332"
      ],
      "liveCheckNote": "Tier 1 assessment was pending; official page still listed Tier 2 at verification.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 2",
        "liveCheckNote": "Tier 1 assessment was pending; official page still listed Tier 2 at verification."
      }
    },
    {
      "id": "R7-SDK08",
      "language": "Swift",
      "officialTier": "Tier 3",
      "currentStableLine": "Current repository release",
      "highestDocumentedProtocol": "Not established as complete for 2026-07-28",
      "olderRevisions": "Earlier protocol support varies",
      "autoDetectionFallback": "Not established",
      "serverDualEraSupport": "Not established",
      "confidence": "VERIFIED tier / INCOMPLETE support",
      "packageSourceIds": [
        "S051",
        "S071"
      ],
      "sourceIds": [
        "S138",
        "S082"
      ],
      "liveCheckNote": "Review release notes and conformance status before use.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 3",
        "liveCheckNote": "Review release notes and conformance status before use."
      }
    },
    {
      "id": "R7-SDK09",
      "language": "PHP",
      "officialTier": "Tier 3",
      "currentStableLine": "Current official line",
      "highestDocumentedProtocol": "Dual-era behavior documented, but tier audit indicates incomplete conformance",
      "olderRevisions": "Handshake-era compatibility documented",
      "autoDetectionFallback": "Documented in protocol-version guide",
      "serverDualEraSupport": "Documented",
      "confidence": "VERIFIED with qualification",
      "packageSourceIds": [
        "S051",
        "S069",
        "S070"
      ],
      "sourceIds": [
        "S138",
        "S333",
        "S334"
      ],
      "liveCheckNote": "Protocol documentation does not erase Tier 3 conformance limitations.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 3",
        "liveCheckNote": "Protocol documentation does not erase Tier 3 conformance limitations."
      }
    },
    {
      "id": "R7-SDK10",
      "language": "Kotlin",
      "officialTier": "Tier 3",
      "currentStableLine": "Current repository release",
      "highestDocumentedProtocol": "Not established as complete for 2026-07-28",
      "olderRevisions": "Implementation varies",
      "autoDetectionFallback": "Not established",
      "serverDualEraSupport": "Not established",
      "confidence": "VERIFIED tier / INCOMPLETE support",
      "packageSourceIds": [
        "S051",
        "S072"
      ],
      "sourceIds": [
        "S138",
        "S080"
      ],
      "liveCheckNote": "Review open 2026 implementation work and current conformance.",
      "checkedAt": "2026-08-26",
      "packageSnapshot": {
        "officialTier": "Tier 3",
        "liveCheckNote": "Review open 2026 implementation work and current conformance."
      }
    }
  ]
}