WebMCP: browser tools for WorldMonitor

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Choose the right surface

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Availability

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Production origin trial

• https://www.worldmonitor.app
• https://tech.worldmonitor.app
• https://finance.worldmonitor.app
• https://commodity.worldmonitor.app
• https://happy.worldmonitor.app
• https://energy.worldmonitor.app

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Local development

1. Open chrome://flags/#enable-webmcp-testing.
2. Set WebMCP for testing to Enabled.
3. Relaunch Chrome completely.
4. Start WorldMonitor locally. Open /dashboard for the eight-tool dashboard, not /embed. To inspect the static two-tool homepage, first run npm run build:pro, then open /pro/welcome.html. The local Vite route / loads the dashboard SPA; only production rewrites / to the welcome page.
5. Confirm feature detection in DevTools:

Boolean(document.modelContext?.registerTool)

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Tool inventory

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Homepage tools

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Dashboard imperative tools

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Declarative procurement tool

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Human control and UI behavior

• Imperative tools register synchronously at startup, but wait for the necessary UI or map renderer before acting. Destroying the app aborts pending work and unregisters its tools; same-document reinitialization does not create duplicates.
• Actions go through the same UI, agent-bus, panel, and map paths used by human controls. They do not call a privileged backend shortcut.
• Authentication, subscription entitlement, dashboard variant, mounted-panel availability, layer policy, and renderer readiness are evaluated at invocation time. A tool discovered while signed in cannot retain access after sign-out or downgrade.
• Successful mutations remain visible: panels open, the search palette appears, map state changes, and the declarative procurement form shows active/pending state.
• Denied, invalid, skipped, unavailable, and expired operations return bounded outcomes or safe errors. They do not silently bypass a lock or invent a result.
• The person can continue using the page. Existing reset, close, navigation, and cancellation controls remain authoritative.

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Security and privacy

• Production dashboard responses use Origin-Agent-Cluster: ?1 and a Permissions-Policy containing tools=(self).
• WorldMonitor does not grant WebMCP access to another origin with fromOrigins, exposedTo, or an iframe allow="tools" delegation.
• /embed and /embed.html explicitly send tools=(). An embedded WorldMonitor panel must expose no WebMCP tools, even when its parent page has WebMCP access.
• WebMCP uses the person’s existing browser session. It does not accept a new API key through tool arguments or weaken panel and data entitlements.
• Dashboard search results are treated as untrusted content and are revalidated before selection.
• Dashboard operational telemetry is bounded: webmcp-registered records toolCount, pageSurface, and the API bucket; webmcp-registration-failed records the tool and a stable reason; webmcp-tool-invoked records the tool, outcome, and terminal reason. Dashboard search may additionally record query length, result count, and allowlisted result-type buckets. These WebMCP-specific custom properties must not include arguments, search text, result keys, returned content, URLs, tender content, or user identity. The events still use WorldMonitor’s normal Umami page and session envelope, which includes page context and may be associated with the signed-in dashboard identity; the restricted path omits automatic content-attribution properties, not normal analytics session metadata.

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Debug with the browser API

const modelContext = document.modelContext;
const tools = await modelContext.getTools();
console.table(tools.map(({ name, description }) => ({ name, description })));

const tool = tools.find(({ name }) => name === 'search_dashboard');
const schema = JSON.parse(tool.inputSchema);
console.log(schema);

const result = await modelContext.executeTool(
  tool,
  JSON.stringify({ query: 'Hormuz', scope: 'all', limit: 5 }),
);
console.log(result);

const controller = new AbortController();
const pending = modelContext.executeTool(
  tool,
  JSON.stringify({ query: 'shipping disruption' }),
  { signal: controller.signal },
);
controller.abort();
try {
  await pending;
  throw new Error('Expected the aborted execution to reject.');
} catch (error) {
  if (error?.name !== 'AbortError') throw error;
  console.log('Execution cancelled with AbortError.');
}

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Release smoke checklist

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Local, same SHA

(
  set -euo pipefail
  WEBMCP_SHA="$(git rev-parse --verify HEAD)"
  test "${#WEBMCP_SHA}" -eq 40
  test -z "$(git status --porcelain --untracked-files=normal)"
  printf 'Testing WebMCP at %s\n' "$WEBMCP_SHA"
  WM_WEBMCP_DEPLOYED_SHA="$WEBMCP_SHA" npm run test:e2e:webmcp
)

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Production, same SHA

WM_WEBMCP_PRODUCTION_URL=https://www.worldmonitor.app \
WM_WEBMCP_DEPLOYED_SHA='<40-character-git-sha>' \
npm run test:e2e:webmcp:production

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Compatibility and removal policy

1. Name the exact browser/API gap and keep the current API as the preferred path.
2. Preserve same-origin policy, visible UI behavior, auth/entitlement checks, bounded outputs, privacy rules, and cancellation.
3. Have contract tests for both native and fallback paths plus an explicit removal owner and Chrome milestone or production verification condition.
4. Be removed once the supported current API is verified in production; a fallback must never become an undocumented permanent API.

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Feedback and official references

• Chrome WebMCP overview
• Imperative API
• Declarative API
• WebMCP compared with MCP
• Best practices
• Security guidance
• Evaluation guidance
• Chrome 149 origin-trial announcement
• Chrome DevTools 149 WebMCP inspector