> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentfront.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Observability

> Built-in OpenTelemetry tracing, structured logging, and per-request log collection

FrontMCP has native observability built in. Enable it with a single config line and get automatic distributed tracing, structured JSON logging, and per-request log collection across your entire server — every tool call, resource read, prompt invocation, auth flow, and transport session.

| Capability                 | What It Does                                                           |
| -------------------------- | ---------------------------------------------------------------------- |
| **OpenTelemetry tracing**  | Automatic spans for all 33 SDK flows with parent-child hierarchy       |
| **Structured logging**     | JSON log entries with trace correlation, sent to any backend           |
| **Request log collection** | Per-request aggregated view of all events during a request lifecycle   |
| **`this.telemetry` API**   | Developer-facing API for custom spans, events, and attributes in tools |
| **Vendor integrations**    | OTLP, Coralogix, Datadog, Logz.io, Grafana, winston, pino              |

***

## How It Works

```typescript theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
@FrontMcp({
  observability: true, // That's it
})
```

When enabled:

* **Zero config** — 103+ hooks register automatically on every flow
* **Single trace ID** — all spans in a request share the same W3C trace ID
* **Privacy-safe session ID** — a truncated SHA-256 hash, never the real session ID
* **Zero overhead when unused** — without a TracerProvider, all OTel calls are no-ops
* **MCP-interoperable** — uses `rpc.system = "mcp"` and `mcp.*` attributes for cross-framework tracing

***

## What Gets Instrumented

Every flow in the SDK is automatically traced:

| Category             | Flows                                                                 |
| -------------------- | --------------------------------------------------------------------- |
| **HTTP & Transport** | HTTP requests, SSE sessions, Streamable HTTP, Stateless HTTP          |
| **Tools**            | call-tool (every stage), list-tools                                   |
| **Resources**        | read-resource, list-resources, list-templates, subscribe, unsubscribe |
| **Prompts**          | get-prompt, list-prompts                                              |
| **Agents**           | call-agent (with nested tool call tracking)                           |
| **Auth**             | auth:verify, session:verify                                           |
| **OAuth**            | token, authorize, callback, provider-callback, register               |
| **Skills**           | search, load, llm-txt, llm-full-txt, API                              |
| **Elicitation**      | request, result                                                       |
| **Other**            | completion, well-known endpoints, logging/set-level                   |

***

## Logging vs Tracing

They're complementary, not competing:

|                | Logging                           | Tracing                                  |
| -------------- | --------------------------------- | ---------------------------------------- |
| **What**       | Event stream — discrete log lines | Request lifecycle — spans with timing    |
| **Purpose**    | Debug, audit, error forensics     | Performance analysis, dependency mapping |
| **Export to**  | Stdout, winston, pino, OTLP       | OTLP, Jaeger, Zipkin                     |
| **Connection** | `trace_id` on every log line      | Native parent-child span tree            |

A log line says "what happened." A span says "how long it took." When both share the same `trace_id`, platforms like Coralogix or Datadog show logs inline within a trace waterfall.

***

## Learn More

<CardGroup cols={2}>
  <Card title="Setup Guide" icon="rocket" href="/frontmcp/guides/observability">
    Step-by-step: install, configure backends, use this.telemetry
  </Card>

  <Card title="Telemetry API Reference" icon="code" href="/frontmcp/sdk-reference/telemetry">
    Full API for TelemetryAccessor, TelemetrySpan, and testing utilities
  </Card>

  <Card title="OpenTelemetry" icon="globe" href="https://opentelemetry.io/docs/">
    OpenTelemetry documentation
  </Card>

  <Card title="Plugin System" icon="puzzle-piece" href="/frontmcp/features/plugin-system">
    How plugins hook into the request lifecycle
  </Card>
</CardGroup>