Obs+APM for agent stacks
A developer published an eight‑month production stack for LLM agents that treats agents like microservices — using OpenTelemetry + Jaeger traces, structured logs, and a 'suspicion score' (latency + token bloat + divergence) to trigger alerts shared. The pattern frames agent observability as full‑stack APM rather than ad‑hoc logging, making incidents and hallucinations traceable across retrieval, model, and orchestration boundaries.
Instrumentation marks LLM calls and tool executions as OpenTelemetry spans using the gen_ai.* semantic conventions (youtube.com). Traces are exported to a Jaeger v2 backend over OTLP for visualization and span storage (Jaeger V2 supports OTLP ingestion and works as a trace backend for OpenTelemetry). (docs.dapr.io) The shared "suspicion score" combines per‑turn latency, measured token bloat, and divergence from expected outputs — an approach analogous to extract‑and‑evaluate monitoring where per‑turn suspicion is aggregated (the referenced research aggregates the second‑highest turn and applies an audit threshold). (arxiv.org) Tracing links retrieval spans (vector DB or search), model invocation spans, and orchestration spans so incidents and hallucinations can be root‑caused across boundaries, a pattern echoed in agent observability blueprints and practical tracing guides. (oneuptime.com) The stack pairs OpenTelemetry traces with APM workflows via OpenTelemetry→APM bridges (examples include Elastic’s OTEL bridge and vendor APMs ingesting OTLP), enabling alerts and SLO enforcement on combined trace+metric signals. (elastic.co) Operational caveats surfaced in the thread include controlling trace volume with sampling strategies (head vs tail sampling), measuring token generation as the dominant latency/cost factor, and using agent‑centric dashboards (AgentStack/AgentOps‑style session drilldowns) to triage incidents; reducing output tokens is a common latency lever (roughly proportional reductions in tokens yield similar latency gains per vendor guidance). (dev.to)
