| name | interpreting-eval-harness-evaluations |
| description | Monitor and interpret evaluation runs of the eval-harness framework. Use when asked to watch, interpret, debug or diagnose an eval run, its logs, its scores or its results. |
Overview
This guide covers how to monitor an eval-harness run
while it is in progress, interpret the logs and results once it finishes, and diagnose the
failures that can occur along the way.
Locate the run
Every run writes to its own directory: <OUTPUT_DIR>/<YYYYMMDD_HHMMSS>_<session_id>/, where
OUTPUT_DIR is set by EVAL_HARNESS_OUTPUT_DIR (default output). Inside it:
session.log - every record from every agent thread, interleaved.<agent_type>_<model>[_<effort>].log - one per agent, containing only that agent's records.
Characters that cannot appear in a filename (e.g. / in model names) are replaced with _.results.json (or results.csv) - written when the session finishes; see the
Results File Schema for the field-by-field breakdown.
Read the logs
Log lines are formatted <timestamp> - <level> - <file:line> - <message>. The markers to look
for:
--- arrange phase --- / --- act phase --- / --- score phase --- - phase boundaries.[arrange] <line> (likewise [act] and [score]) - stdout/stderr streamed from inside the
container, including every print() in the eval's phase methods.Run 1/3 - logged when an eval has run_count > 1; each run is a fresh container.EVAL_TOTAL_TOKENS=<int> - emitted once per agent-shell call and summed into the token totals.EVAL_SCORE=<float> - printed by the eval's score method; the harness takes the last
occurrence in the score phase output. If no line matches, the run silently scores 0.0.phase <label> completed - the phase finished cleanly.
In the results file, an eval's score is the mean across its runs, while total_tokens and
time_taken_seconds are totals across them.
Monitor a live run
tail -f the session log, or a single agent's log for less noise. A failing agent does not stop
the others: it is logged as Agent <type>-<model> failed with a traceback, marked FAILED, and
the session carries on. At the end, main.py prints one FAILED: ... line per failed agent and
exits with code 1.
Diagnose failures
| Symptom | Likely cause | Where to look |
|---|
RuntimeError: ... not configured or ... auth file not found, before any phase marker | Missing or expired credentials for that agent | Authorisation |
<phase> failed (exit <N>) followed by a --- container output --- block | The phase script raised; the block holds the full traceback | The traceback; for arrange, also external dependencies (repo clones, MCP servers) |
<phase> timed out after <N>s (exit 124 or 137) | The phase exceeded its timeout | EVAL_HARNESS_<ARRANGE|ACT|SCORE>_TIMEOUT_SECONDS, defaults 3600/3600/600 |
NameError or ImportError in a phase traceback | The eval violates an authoring constraint (module-level state, imports outside the method body) | Constraints in the eval creation skill |
TypeError: <Class> must be a class implementing arrange/act/score | The eval class does not satisfy the EvaluationFile protocol | Same constraints section |
| Score is 0.0 with no error | The score method never printed EVAL_SCORE= (or the agent genuinely scored zero) | The [score] output for that run |
Malformed score line | EVAL_SCORE= was printed with a non-float value | The eval's score method |
total_tokens is 0 but the agent clearly did work | Stale docker image (agent-shell version mismatch) | Rebuild the images - see the commands in AGENTS.md |
ValueError: I/O operation on closed file after the end-of-run summary | Benign docker-py teardown noise | Ignore it |
Where the fix belongs
Classify the failure before changing anything:
- The eval itself (authoring constraint violations, scoring bugs) - fix the eval class,
following the eval creation skill.
- Harness configuration (timeouts, output locations) -
.env / EVAL_HARNESS_ environment
variables, documented in Configuration.
- Credentials - re-authenticate on the host per the
authorisation guide.
- The docker image - rebuild manually after any Dockerfile or agent-shell change; there is no
auto-rebuild.
