Inspect

simple-webmcp now ships inspect tools so you can see the same tools agents see — without an LLM.

Programmatic — simple-webmcp/inspect

import { listTools, invokeTool, onToolsChanged, isSupported } from 'simple-webmcp/inspect';

// list registry + native getTools()
listTools(); // -> {name, description, inputSchema, status, source}[]

// async variant that awaits modelContext.getTools()
import { listToolsAsync } from 'simple-webmcp/inspect';
await listToolsAsync();

// invoke same path an agent would
await invokeTool('add_to_cart', { productId: 'keyboard', quantity: 1 });

// subscribe to toolchange (Chrome) or poll fallback
const off = onToolsChanged((tools) => console.log(tools));
off();

• listTools() merges registry.list() (our wrapper) and document.modelContext.getTools() / listTools() if native.
• invokeTool(name, args) tries modelContext.executeTool / invokeTool / callTool, then registry fallback and shim _tools.
• Works with simple-webmcp/dev-polyfill shim in dev (in-memory).

React — simple-webmcp/devtools

import { Inspector } from 'simple-webmcp/devtools';

export function DevPanel() {
  return <Inspector defaultOpen />;
}

Inspector is 'use client', shows:

• WebMCP supported vs unsupported (dev shim)
• Each tool: name, description, status (registered/unsupported), source, inputSchema (collapsible), annotations
• Per-tool Invoke with JSON textarea, example prefilled from inputSchema, result / error display
• Polls via onToolsChanged

Import from simple-webmcp/devtools — separate entry 16KB raw, not in core. Use only in dev.

Demo — shopping cart

The interactive demo at /demo/ and /demo/index.html (static examples/demo + docs/public/demo) wires:

const addToCartTool = webmcp(addToCart, { description: 'Add product', fields: {...} });
await addToCartTool.register();

The Inspect panel below lists add_to_cart via simple-webmcp/inspect and lets you invoke with {"productId":"keyboard","quantity":1} — same as the agent.

Try npm run docs:dev → open /demo/ (http://localhost:5173/simple-webmcp/demo/) and open the Inspect card.