Bare Eval — Isolated Evaluation Calls
Run claude -p --bare for fast, clean eval/grading without plugin overhead.
CC 2.1.81 required. The --bare flag skips hooks, LSP, plugin sync, and skill directory walks.
When to Use
- Grading skill outputs against assertions
- Trigger classification (which skill matches a prompt)
- Description optimization iterations
- Any scripted
-pcall that doesn't need plugins
When NOT to Use
- Testing skill routing (needs
--plugin-dir) - Testing agent orchestration (needs full plugin context)
- Interactive sessions
Prerequisites
# --bare requires ANTHROPIC_API_KEY (OAuth/keychain disabled)
export ANTHROPIC_API_KEY="sk-ant-..."
# Verify CC version
claude --version # Must be >= 2.1.81Quick Reference
| Call Type | Command Pattern | |
|---|---|---|
| Grading | claude -p "$prompt" --bare --max-turns 1 --output-format text | |
| Trigger | claude -p "$prompt" --bare --json-schema "$schema" --output-format json | |
| Streaming grade | claude -p "$prompt" --bare --max-turns 1 --output-format stream-json | |
| Optimize | `echo "$prompt" \ | claude -p --bare --max-turns 1 --output-format text` |
| Force-skill | claude -p "$prompt" --bare --print --append-system-prompt "$content" | |
| @-file in prompt | claude -p "grade @fixtures/case-1.md against rubric" --bare (CC 2.1.113 Remote Control autocomplete) |
--output-format stream-json
Newline-delimited JSON events (one per token/tool-call) — lets a runner score partial output or abort early on a failing probe without waiting for the full response.
claude -p "$prompt" --bare --max-turns 1 --output-format stream-json \
| while IFS= read -r line; do
# line is a single JSON event; inspect $.type == "content_block_delta"
jq -r 'select(.type == "content_block_delta") | .delta.text' <<< "$line"
doneUse stream-json over json when:
- grading long outputs and you want incremental scoring,
- piping into another CLI step-by-step (e.g.
ork:eval-runner), - you need per-token timing data alongside the content.
Invocation Patterns
Load detailed patterns and examples:
Read("${CLAUDE_SKILL_DIR}/references/invocation-patterns.md")Grading Schemas
JSON schemas for structured eval output:
Read("${CLAUDE_SKILL_DIR}/references/grading-schemas.md")Pipeline Integration
OrchestKit's eval scripts (npm run eval:skill) auto-detect bare mode:
# eval-common.sh detects ANTHROPIC_API_KEY → sets BARE_MODE=true
# Scripts add --bare to all non-plugin calls automaticallyBare calls: Trigger classification, force-skill, baseline, all grading. Never bare: run_with_skill (needs plugin context for routing tests).
Performance
| Scenario | Without --bare | With --bare | Savings |
|---|---|---|---|
| Single grading call | ~3-5s startup | ~0.5-1s | 2-4x |
| Trigger (per prompt) | ~3-5s | ~0.5-1s | 2-4x |
| Full eval (50 calls) | ~150-250s overhead | ~25-50s | 3-5x |
Rules
Read("${CLAUDE_SKILL_DIR}/rules/_sections.md")Troubleshooting
Read("${CLAUDE_SKILL_DIR}/references/troubleshooting.md")Related
eval:skillnpm script — unified skill evaluation runnereval:trigger— trigger accuracy testingeval:quality— A/B quality comparisonoptimize-description.sh— iterative description improvement- Version compatibility:
doctor/references/version-compatibility.md