TraceGate: An LLM Agent Observability Gate

The Core Concept #

The goal is to move beyond "did it get the right answer?" to "did it get the answer for the right reasons, and is it traceable?" If an agent run doesn't produce the required telemetry evidence, TraceGate blocks the release.

I define these requirements in a YAML contract. For example, I can set strict budgets for latency, cost, and tool retries:

name: TraceGate AI Agent Release Contract
serviceName: tracegate-demo-agent

budgets:
 maxRunCostUsd: 0.005
 maxP95LatencyMs: 2000
 maxToolRetries: 1

checks:
 - id: span-agent-run
 type: required-span
 spanName: agent.run
 severity: critical

![TraceGate: An LLM Agent Observability Gate](/uploads/articles/064988dbdf9ccd46.jpg)

 - id: span-llm-call
 type: required-span
 spanName: llm.call
 severity: critical

 - id: attr-llm-model
 type: required-attribute
 spanName: llm.call
 attribute: gen_ai.request.model
 severity: critical

 - id: retry-budget-trace-lookup
 type: max-tool-retries
 toolName: trace.lookup
 maxRetries: 1
 severity: critical

If a tool like trace.lookup

retries three times but the contract limit is one, TraceGate flags a critical failure and blocks the deployment.

Technical Implementation #

This is essentially a deep dive into an AI workflow integrated with a monitoring stack. The pipeline follows this sequence:

Scenario → Agent runner → OpenTelemetry → SigNoz → TraceGate contract evaluator → Pass/Block.

The backend is Node.js, using OTLP HTTP exporters to push spans and metrics to SigNoz. Here is the OpenTelemetry SDK configuration I used for the deployment:

const endpoint =
 process.env.OTEL_EXPORTER_OTLP_ENDPOINT ?? "http://localhost:4318";

const sdk = new NodeSDK({
 traceExporter: new OTLPTraceExporter({
 url: `${endpoint}/v1/traces`
 }),
 logRecordProcessor: new BatchLogRecordProcessor(
 new OTLPLogExporter({
 url: `${endpoint}/v1/logs`
 })
 ),
 metricReader: new PeriodicExportingMetricReader({
 exporter: new OTLPMetricExporter({
 url: `${endpoint}/v1/metrics`
 }),
 exportIntervalMillis: 1000
 })
});

By tracking spans like llm.call

and tool.policy.search

, I can verify that the agent is following the intended logic path rather than stumbling upon the right answer by accident. For anyone building an LLM agent, treating observability as a deployment requirement—rather than an afterthought—is the only way to avoid production nightmares.

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