prompt-eval-debug

prompt-eval-debug is a skill for Claude Code, Cursor from emaraschio/cursor-commands. It costs 73 tokens per session (1,161 once invoked), scanned A, original, MIT.

A prompt-debugging workflow for improving instructions given to an AI system. It creates a small set of example cases, including normal, edge, and capability-limit cases, to test how the prompt behaves.

In plain words
What is it for?
Use it to evaluate prompts, diagnose unexpected answers, propose the smallest useful revision, and create stable test cases for future checks.
Why use it?
It helps distinguish a faulty prompt from a missing tool, unsupported capability, or broken workflow, so changes can target the real problem.

Skill for Claude CodeCursor

Written for Claude Code and Cursor: user-invocable in frontmatter, but also installed under .cursor/. Also seen: mentions Codex.

Good fit Use it to evaluate prompts, diagnose unexpected answers, propose the smallest useful revision, and create stable test cases for future checks.

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Install with agentmods
npx agentmods add skills/emaraschio/cursor-commands/prompt-eval-debug
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add emaraschio/cursor-commands --skill prompt-eval-debug
Clone the repo
git clone --depth 1 https://github.com/emaraschio/cursor-commands

Made for: Claude Code, Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for prompt-eval-debug

README.md
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Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for prompt-eval-debug

Your own site · 80×15
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Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,161 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00073 $0.01161
Opus 5 $0.00036 $0.00580
Sonnet 5 $0.00015 $0.00232
Haiku 4.5 $0.00007 $0.00116

Measured 5d ago against content hash 8cac7b067142, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

prompt-eval-debug scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/skill-contracts/prompt-eval-debug/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Prompt eval debug

Role

You act as a prompt debugger for an arbitrary prompt the user is iterating on. You help them improve it by designing a tiny eval suite, classifying failures, and suggesting the smallest next change, not a blind full rewrite. You do not claim this repository's CI scored their ad-hoc suite.

When to use

Use when a prompt or skill underperforms and the user might otherwise rewrite it on vibes. For shipped commands in this catalog, stable cases eventually belong in skill-contracts/<name>/eval/cases.md per EVAL_GUIDE.md. For delegation design before autonomous work, use define-agent-goal. For code/runtime bugs, use debug-issue.

Workflow

Run phases in order.

Phase 0: Intake

  1. Require Prompt (paste the prompt under test) and Task (what the AI should do when given that prompt).
  2. If either is missing, ask one focused question for each gap before proceeding.
  3. Produce a one-paragraph summary of what the prompt is trying to accomplish.

Phase 1: Tiny eval suite

Produce exactly five cases in a table with columns: ID, Type, Input / scenario, Expected behavior, Notes.

ID Type Requirement
C0 control Should always pass when the prompt is healthy
E1 to E3 edge Scenarios where the prompt could fail; use prior failure modes if the user supplied them
B1 capability-boundary Agent should escalate, ask for help, or refuse (not hallucinate success)

Cases must use concrete inputs and expected behaviors, not vague "should work."

Phase 2: Run guidance

Tell the user to run each case against the current prompt (manual chat, script, or their harness). Do not execute the target prompt as production traffic unless the user explicitly asks you to run a case. Do not claim automated pass/fail scores unless the user reports results.

Phase 3: Diagnosis

For each case (or for failures the user reports), classify the root cause as exactly one primary type:

Read the full file on GitHub · 97 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 97 lines · 73 tokens per session scan A 8cac7b067142

Subscribe to this mod's changes

prompt-eval-debug is a skill published in the GitHub repository emaraschio/cursor-commands (9 stars, last pushed 1mo ago), licensed MIT. It adds 73 tokens to every session and 1,161 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.