PostHog

Enable it

npx klaridian generate --spec ./api.yaml --out ./my-server --plugin posthog

Every tool call sends a PostHog event with the tool name, how long it took, and whether it succeeded. This tells you which tools get used—OpenTelemetry tells you if a call is slow or broken, but not whether anyone's calling it.

Configure it

POSTHOG_API_KEY=phc_... \
POSTHOG_HOST=https://app.posthog.com \
node dist/src/index.js

Why this is a separate plugin from OTel

Tracing has one open standard—OpenTelemetry—so one otel plugin works with every backend. Product analytics doesn't have that: PostHog, Amplitude, and Mixpanel each need their own integration. posthog is the first; amplitude and mixpanel work the same way.

One plugin at a time

Today you can pick one plugin per server—otel, or one of the analytics plugins, not both together. Combining an engineering plugin and a product plugin on the same server is planned, not built yet.

Using FastMCP instead?

If you're building with Python's FastMCP directly rather than generating with klaridian, there's a standalone PostHogMiddleware you can add with mcp.add_middleware(PostHogMiddleware(...)).