AI agent evaluation observability

Evals, Observability & Failure Modes

Evaluate task behavior before launch and observe complete runs after deployment.

DIFFICULTY
Advanced
EST. TIME
65 min
UPDATED
2026-08-19
On this page
  1. 01Definition
  2. 02Why it matters
  3. 03Step by step
  4. 04Build it
  5. 05Failure modes
  6. 06Production notes
  7. 07Sources

Learning objectives

  • Build task-specific offline and online evaluations
  • Trace model, tool, state, policy, and human decisions
  • Turn incidents and reviewer corrections into regression cases

Prerequisites

A versioned agent spec · Representative task examples · A grading rubric

Answer first

Canonical definition

Agent evaluation measures whether a system completes a defined task within quality, policy, cost, and reliability bounds; observability records the run so failures can be diagnosed and reproduced.

Operating context

Why it matters

A final answer score cannot explain whether the agent retrieved bad evidence, selected the wrong tool, repeated an action, or exceeded its mandate.

Production traces become useful only when they are tied to versions, user outcomes, and a failure taxonomy.

Method

Step by step

  1. 01

    Build the case set

    Include common tasks, hard cases, policy boundaries, missing data, tool failures, malicious inputs, and costly mistakes.

  2. 02

    Grade multiple dimensions

    Score task result, evidence, policy compliance, tool choice, state change, latency, and full cost.

  3. 03

    Trace the run

    Correlate model requests, retrieved context, tool calls, validations, approvals, state transitions, and final outcome.

  4. 04

    Close the regression loop

    Convert production incidents, rejects, and surprising successes into versioned tests before the next release.

Hands-on lab

Create a 25-case agent eval

Assemble a balanced test set for one agent and compare two prompt or model versions.

Deliverable

A rubric, labeled cases, automated checks, trace links, score report, and release threshold.

What breaks

Common failure modes

  • F1Evaluating only the final prose and ignoring actions
  • F2Using a model judge without calibration against human decisions
  • F3Collecting traces that omit versions, permissions, or state changes

Beyond the demo

Production notes

  • Redact or hash sensitive data while keeping enough identifiers to investigate authorized incidents.
  • Monitor distribution shift, tool error rates, human override, cost, and stuck-loop signals—not only average score.

Further reading

Sources

  1. [1]NIST AI RMF: Measure
  2. [2]Anthropic: Building effective agents

Related Tenten resources

From capstone to production

A working demo is the beginning of the engineering problem.

Tenten helps teams scope one agentic workflow, integrate real data and permissions, define evals and handoffs, and own the path through launch and on-call.