{
  "slug": "webmcp-debugging-tools-appear-in-third-party-developer-tools-5f63778c3187",
  "title": "WebMCP debugging tools appear in third-party developer tools",
  "tools": [
    "chrome-devtools-mcp"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-10-15T14:01:41.000Z",
  "announced_at": "2026-10-15T14:01:41.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When a page exposes WebMCP tools, enable the WebMCP category and Chrome’s WebMCP feature; enable the third-party category to list and execute tools marked `annotations.debugging === true`. Use the regular WebMCP tools for other WebMCP tools.",
    "examples": [
      "list_3p_developer_tools({\"pageId\": <pageId>}) → execute_3p_developer_tool({\"pageId\": <pageId>, \"toolName\": \"<toolName>\", \"params\": \"<JSON-stringified parameters>\"})",
      "list_webmcp_tools({\"pageId\": <pageId>}) → execute_webmcp_tool({\"pageId\": <pageId>, \"toolName\": \"<toolName>\", \"input\": \"<JSON-stringified parameters>\"})",
      "npx chrome-devtools-mcp@1.11.0 --categoryExperimentalThirdParty=true --categoryExperimentalWebmcp=true --chromeArg=--enable-features=WebMCP"
    ],
    "gotchas": [
      "Version: 1.11.0",
      "--categoryExperimentalThirdParty=true (required): Enables third-party developer tools exposed by the inspected page, including debugging WebMCP tools.",
      "--categoryExperimentalWebmcp=true (required): Enables WebMCP tools, excluding debugging tools served by the third-party category.",
      "--enable-features=WebMCP (required): Chrome launch flag required to enable WebMCP; the docs specify Chrome 150+.",
      "pageId (required): Targets a specific page by ID for listing or execution.",
      "toolName (required): Name of the tool to execute.",
      "params: JSON-stringified parameters passed to a third-party developer tool.",
      "input: JSON-stringified parameters passed to a WebMCP tool.",
      "Prerequisite: Use Chrome 150+ and launch it with `--enable-features=WebMCP`.",
      "Prerequisite: Enable `--categoryExperimentalThirdParty=true` for third-party/debugging WebMCP tools and `--categoryExperimentalWebmcp=true` for regular WebMCP tools. Both categories are disabled by default.",
      "WebMCP tools require Chrome 150+ with `--enable-features=WebMCP`.",
      "WebMCP tools require `--categoryExperimentalWebmcp=true`; debugging tools are exposed under the third-party developer tools category.",
      "Third-party developer tools require `--categoryExperimentalThirdParty=true`."
    ]
  },
  "why_it_matters": "When debugging a page that exposes WebMCP debugging tools, list and execute those tools through the third-party developer tools category.",
  "sources": [
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/releases/tag/chrome-devtools-mcp-v1.11.0",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/pull/2900",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/0db519f079336df8265ee5ccae47ae5c57695e51/docs/tool-reference.md",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/0db519f079336df8265ee5ccae47ae5c57695e51/docs/configuration.md"
  ],
  "rank": 0.91028,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v2+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "daily-20261015-20",
    "verdict_id": "daily-20261015-20:daily-20261015-20-0fad988eee015972-12:gate",
    "evidence_hash": "f4ab448bcf93bfbc244c11495c3319bca957c64c1a6b2148d3c22048468b33a0"
  },
  "review": {
    "draft_hash": "1613a8b6b51189d6901464138dfd1e3bd60f5f8694c1043698d9de4ac6dbeb23",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-15T14:01:41.000Z",
    "decision": "daily-20261015-20:gate",
    "reason": "2 of 3 judge runs approved with p_yes >= 0.9 (mean 0.91 >= 0.9; 2 needed) and Jev gave 0.66 (>= 0.6 needed)."
  }
}