listToolDescriptors

Lists the WebMCP tools registered on this page right now, as a model reads them.

Lists the WebMCP tools registered on this page right now, as a model reads them. Use it in an adapter or a request of your own that does not go through the session.

Import

import { listToolDescriptors } from "@webmcp-agents/chat";
import type { ToolDescriptor } from "@webmcp-agents/chat";

Example

Send the page’s current tools with a chat request.

import { listToolDescriptors } from "@webmcp-agents/chat";

// The tools on this page right now, as a model reads them.
const tools = await listToolDescriptors();

const res = await fetch("/api/chat", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    messages: [
      {
        id: "u-1",
        role: "user",
        parts: [{ type: "text", text: "Hi" }],
      },
    ],
    tools,
    page: { url: location.href },
  }),
});
console.log(res.status);

Options

None. listToolDescriptors() takes no arguments and reads document.modelContext at the moment you call it.

Returns

A Promise<ToolDescriptor[]> from document.modelContext.getTools(). A ToolDescriptor is { name, description, inputSchema }.

Tools whose origin is another origin are left out (Chrome reports where a tool lives).
description falls back to the tool’s title, then its name.
inputSchema is parsed when it is a JSON string. A missing or unreadable schema becomes { type: "object", properties: {} }.
Without document.modelContext (no WebMCP, or on the server) it resolves to [].

Notes

Tools change as the page changes (a route swaps, a form hides itself). Read the list again before every model call; useAgentSession refreshes it on every toolchange and after each tool call.
It rejects if getTools() rejects; useAgentSession treats that as an empty list.