WebMCP installation for MCP Analytics

If your web app registers tools with WebMCP, posthog-js captures each tool call as a $mcp_tool_call event.

Enable capture

posthog.init("<ph_project_token>", {
    api_host: "https://us.i.posthog.com",
    capture_webmcp: true,
})

Initialize PostHog before your app registers its tools. The SDK does not instrument tools that register earlier.

Intent and model

By default, the SDK adds a context field (the agent's reason for the call) and an llm_model field to your tool schemas. It removes them before it calls your tool. To turn off either field:

posthog.init("<ph_project_token>", {
    api_host: "https://us.i.posthog.com",
    capture_webmcp: {
        intent: true,
        model: false,
    },
})

If you change these settings, register your tools again.

Failed calls in Error Tracking

If exception autocapture is enabled, a failed tool call also sends an $exception event. With the slim bundle, add ErrorTrackingExtensions next to WebMCPExtensions.

Privacy

The SDK does not capture tool arguments or tool results. It redacts credentials and personal data in context and in error messages. Your consent, opt-out, and before_send settings still apply.