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11 Evaluation and Observability

Phase 3 - Systems
Stage 11 of 14. Previous: Stage 10 - Multi-Agent Systems. Next: Stage 12 - Security and Ethics.

Goal

Learn to measure, test, trace, and debug agent systems.

Learn

Start Here

Evaluation is how you decide whether an agent change actually helped. Observability is how you explain what happened when an agent run failed.

For agents, a single final answer is not enough to judge quality. You also need to inspect the steps:

Layer What to measure
Final answer correctness, completeness, tone, groundedness
Tool calls selected tool, arguments, errors, retries, permissions
Retrieval relevant documents found, irrelevant documents avoided
Run behavior latency, token use, cost, loops, stop reason
Production health failure rate, escalation rate, user feedback, incident patterns

Beginner rule:

Do not change prompts, models, tools, or retrieval settings without a small eval set.
Otherwise you are guessing.

Example Team Study Task

Use one realistic support-agent task throughout this stage:

The agent reads a billing ticket, searches policy documents, drafts a reply,
and must not issue refunds or send emails without human approval.

Study it from each evaluation angle:

Topic Example question to answer
Quality metrics What makes the draft good enough to send?
Tool unit tests Does create_refund_draft avoid submitting a real refund?
Flow integration tests Did the agent search policy before drafting?
Prompt regression tests Did a prompt change improve grounding but hurt tone?
RAG evaluation Did retrieval find the correct refund-policy section?
Tracing and logs Can you see each model call, tool call, and stop reason?
Human review Would a support lead approve this draft?
Tools Which platform helps the team run and inspect these checks?

Build

Create an evaluation suite with test cases, expected outcomes, cost tracking, latency tracking, and trace review.

Exit Criteria

  • You can define success metrics before changing prompts or models.
  • You can trace an agent run from user input to final response.
  • You can reproduce and debug failures.
  • You can compare two agent versions with the same eval set.
  • You can separate model quality failures from tool, retrieval, and orchestration failures.

Checkpoint

Use the Stage 11 checkpoint before moving on.