headers Gateway auto-tags every access log entry Filter by session in your observability tool No agent-side instrumentation needed {"session_id":"goose-abc123","method":"POST","path":"/v1/chat/completions", "upstream":"openai","tokens_in":342,"tokens_out":89,"latency_ms":1240} {"session_id":"goose-abc123","method":"POST","path":"/mcp", "upstream":"kiwi","tool":"search-flight","latency_ms":820} {"session_id":"goose-abc123","method":"POST","path":"/v1/chat/completions", "upstream":"openai","tokens_in":1205,"tokens_out":156,"latency_ms":2100}