{
  "title": "WebMCP security annotations",
  "description": "Communicate read-only and untrusted-content hints across the site-to-agent boundary. Draft and implementation support are tracked independently.",
  "slug": "webmcp-security-annotations",
  "locale": "en",
  "seoTitle": "WebMCP security annotations compatibility — Can My Agent Use",
  "socialTitle": "WebMCP security annotations",
  "socialDescription": "Communicate read-only and untrusted-content hints across the site-to-agent boundary. Browser and agent evidence remains revision-specific.",
  "llmSummary": "WebMCP security annotations is an atomic WebMCP capability and does not imply every other part of the draft.",
  "audience": "Web platform architects and agent-tooling engineers.",
  "contentKind": "feature",
  "status": "published",
  "tags": [
    "interfaces",
    "webmcp",
    "web",
    "draft"
  ],
  "updated": "2026-08-28T00:00:00.000Z",
  "published": "2026-08-28T00:00:00.000Z",
  "category": "interfaces",
  "summary": "Communicate read-only and untrusted-content hints across the site-to-agent boundary.",
  "specLabel": "WebMCP draft 2026-08-26",
  "specification": {
    "id": "webmcp",
    "revision": "2026-08-26 draft",
    "maturity": "draft community group report",
    "role": "website, user agent, or browser agent",
    "authority": "W3C Web Machine Learning Community Group",
    "canonicalUrl": "https://webmachinelearning.github.io/webmcp/"
  },
  "aliases": [
    "untrustedContentHint"
  ],
  "capabilityKind": "atomic",
  "parent": "webmcp",
  "related": [],
  "relations": [],
  "highlight": false,
  "notes": [
    {
      "id": 1,
      "text": "Evidence checked 2026-08-28: Chrome's origin-trial documentation exposes `readOnlyHint` and `untrustedContentHint` in registered and discovered WebMCP tools and publishes handling guidance for both hints."
    }
  ],
  "issues": [],
  "resources": [
    {
      "id": "webmcp-draft",
      "title": "WebMCP Draft Community Group Report",
      "href": "https://webmachinelearning.github.io/webmcp/",
      "kind": "spec",
      "publisher": "W3C Web Machine Learning Community Group",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28"
    },
    {
      "id": "chrome-webmcp-security-annotations-api",
      "title": "Chrome for Developers — WebMCP Imperative API",
      "href": "https://developer.chrome.com/docs/ai/webmcp/imperative-api",
      "kind": "docs",
      "publisher": "Google Chrome",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "annotations and discovered tool representation"
    },
    {
      "id": "chrome-webmcp-security-annotations-guidance",
      "title": "Chrome for Developers — WebMCP tool security",
      "href": "https://developer.chrome.com/docs/ai/webmcp/secure-tools",
      "kind": "docs",
      "publisher": "Google Chrome",
      "evidenceType": "documented",
      "reviewedAt": "2026-08-28",
      "locator": "Use annotation hints"
    }
  ],
  "support": [
    {
      "harness": "chrome-webmcp-preview",
      "versions": [
        {
          "track": "current",
          "status": "yes",
          "noteIds": [
            1
          ],
          "target": {
            "kind": "dated-documentation",
            "revision": "Chrome 153 WebMCP origin-trial documentation",
            "observedAt": "2026-08-28"
          },
          "environmentProfile": "preview-enabled",
          "qualifiers": [
            {
              "type": "origin-trial",
              "value": "WebMCP is an experimental origin trial and local testing requires the enable-webmcp-testing flag"
            },
            {
              "type": "policy",
              "value": "annotations are advisory hints to the consuming agent; they do not by themselves enforce read-only behavior or sanitize untrusted output"
            }
          ],
          "evidence": [
            {
              "resourceId": "webmcp-draft",
              "type": "documented",
              "observedAt": "2026-08-28"
            },
            {
              "resourceId": "chrome-webmcp-security-annotations-api",
              "type": "documented",
              "observedAt": "2026-08-28"
            },
            {
              "resourceId": "chrome-webmcp-security-annotations-guidance",
              "type": "documented",
              "observedAt": "2026-08-28"
            }
          ],
          "stage": "experimental"
        }
      ]
    }
  ],
  "html": "/features/webmcp-security-annotations",
  "markdown": "/features/webmcp-security-annotations.md",
  "json": "/api/v1/features/webmcp-security-annotations.json",
  "body": "Communicate read-only and untrusted-content hints across the site-to-agent boundary.\n\nWebMCP is a draft Community Group Report, not a W3C Standard. Positive implementation cells must retain origin-trial, version, permissions, and agent-integration qualifiers."
}