WebMCP debugging tools appear in third-party developer tools
Introduced 2026-10-15 · score 0.91
HOW TO USE IT
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.
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=WebMCPWHY THIS HELPS
When debugging a page that exposes WebMCP debugging tools, list and execute those tools through the third-party developer tools category.
REQUIREMENTS AND LIMITATIONS
- 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`.
FIRST-PARTY EVIDENCE
- 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
Check the installed version and the source before using it. Entry JSON