[rgarcia]

Summary

The API now supports custom WebMCP tools (GET/POST /browsers/{id_or_name}/webmcp/custom-tools, DELETE .../custom-tools/{id}). It also returns tool metadata nested under tool (name, description, inputSchema, MCP-style annotation names) instead of the old flat fields. The generated API reference already covers both, but the hand-written guides still used the flat shape, so their examples broke against the current API and SDK 0.112.0.

New page: browsers/webmcp-custom-tools (nav: after WebMCP)

• page vs cdp tools, the definition fields, and the context a cdp handler receives (matches, signal)
• A worked Hacker News batch (hn-tools.js): a page tool that lists stories and a cdp tool that navigates its tab and returns comments
• Register, discover/invoke, and update/remove examples in TypeScript, Python, Go, and curl
• URL pattern rules, definition IDs vs tool_refs, force_overwrite_namespace, 409/400/404 behavior
• Lifecycle: custom tools live in the browser's REPL process, so a REPL timeout, reset: true, or a crash removes all of them
• REPL webmcp.addCustomTools/listCustomTools/removeCustomTool, limits, and security notes

Updated for the nested shape

• browsers/webmcp: field tables, annotation names, SDK/curl examples, Go ListTools params argument, exclude_custom, and source.custom / source.target_id
• browsers/playwright-execution and browsers/repl: tool.tool.name and tool.inputSchema in the WebMCP helper examples. The REPL page also lists the custom-tool helpers and excludeCustom
• reference/mcp-server/tools/webmcp (+ overview card): new list_custom, add_custom, and remove_custom actions and parameters
• reference/cli/browsers: new WebMCP section covering webmcp list/invoke and webmcp custom-tools list/add/remove (CLI v0.41.0)

Testing

• Ran every code example on the changed pages against the production API on a live browser:
  • The new page's register → invoke → overwrite → remove flow in TypeScript (SDK 0.112.0), Python (0.112.0), Go (v0.112.0), and curl.
  • The webmcp.mdx, Playwright, and REPL examples, using a stand-in search_products custom tool.
  • TypeScript examples type-check with tsc --strict, and Go examples pass go vet.
• Checked the stated behaviors live:
  • 93-character name limit
  • 409 on a duplicate name, 400 on an invalid batch, 204/404 on remove
  • page tools don't validate input, and cdp tools do
  • exclude_custom works
  • Playwright webmcp.listTools() includes custom tools
  • A REPL timeout or reset clears the registry
• Ran the CLI v0.41.0 commands and the MCP add_custom example source against production.
• mint broken-links passes. All changed pages render under mint dev.

Not verified, so the docs don't claim anything about it: whether custom tools survive browser standby/restore or browser-pool reuse. No changelog entry was added.