{
  "slug": "chrome-devtools-mcp-screencast-supports-webm-and-uses-filepath-4b2401135413",
  "title": "chrome-devtools-mcp screencast supports WebM and uses filePath",
  "tools": [
    "chrome-devtools-mcp"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-04-22T17:09:46.000Z",
  "announced_at": "2026-04-22T17:09:46.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When saving an experimental screencast, start recording with `screencast_start` and a `.webm` `filePath`, then stop it with `screencast_stop`.",
    "examples": [
      "screencast_start({\"pageId\": <pageId>, \"filePath\": \"<output>.webm\"})",
      "screencast_stop({\"pageId\": <pageId>})"
    ],
    "gotchas": [
      "Version: 0.23.0",
      "Availability: Experimental screencast command.",
      "pageId (required): ID of the target page.",
      "filePath: Output file path; `.webm` and `.mp4` are supported. A unique path is generated if omitted.",
      "--experimentalScreencast (required): Enables the experimental screencast tools; defaults to false.",
      "--experimentalFfmpegPath: Path to the ffmpeg executable.",
      "Prerequisite: Enable `--experimentalScreencast`; install ffmpeg and ensure it is available in the MCP server PATH.",
      "The screencast command supports `.webm` in addition to `.mp4`."
    ]
  },
  "why_it_matters": "Save an experimental screencast as a WebM file.",
  "before": "The release note says the parameter was previously named `path`.",
  "sources": [
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/releases/tag/chrome-devtools-mcp-v0.23.0",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/pull/1934",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/chrome-devtools-mcp-v0.23.0/src/tools/screencast.ts",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/main/docs/tool-reference.md",
    "https://github.com/ChromeDevTools/chrome-devtools-mcp/blob/main/docs/configuration.md"
  ],
  "rank": 0.90027,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v1+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "ghtools-20261008",
    "verdict_id": "ghtools-20261008:ghtools-20261008-22b0a0119b777f77-2:gate",
    "evidence_hash": "267ab7c7ae665900ccd7d29d4f05f238404df85b34638aa785bf9532aa89eb54"
  },
  "review": {
    "draft_hash": "c9fadd6c73093f0f548958b0f0eb9287820e1c6ff0d96d39b0fd1f69832c3e9a",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-07T00:00:00.000Z",
    "decision": "ghtools-20261008:gate",
    "reason": "2 of 3 judge runs approved with p_yes >= 0.9 (mean 0.90 >= 0.9; 2 needed) and Jev gave 0.76 (>= 0.6 needed)."
  }
}