opencode-simple: Skill for OpenCode

.opencode/skills/eval-harness/SKILL.md

eval-harness is a skill for OpenCode from zhmxiaowo/opencode-simple. It costs 19 tokens per session (1,641 once invoked), scanned A, a copy of eval-harness, MIT.

A framework for testing and measuring coding-agent behavior, using predefined success checks much like unit tests check ordinary software.

In plain words
What is it for?
Use it to define pass/fail criteria, create capability and regression evaluations, measure reliability with pass@k, and compare agent or model versions.
Why use it?
It makes agent changes measurable and helps detect regressions—cases where a new change breaks behavior that previously worked.

Skill for OpenCode

Written for OpenCode: installed under .opencode/. Also seen: mentions Claude Code; mentions OpenCode.

This is zhmxiaowo/opencode-simple's own configuration. It tells OpenCode how to work on opencode-simple itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything opencode-simple configures →

Reuse

Borrowing it

Nothing to install: this file belongs to zhmxiaowo/opencode-simple. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/zhmxiaowo/opencode-simple/main/.opencode/skills/eval-harness/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/zhmxiaowo/opencode-simple

Made for: OpenCode.

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 eval-harness

README.md
[![agentmods](https://agentmods.dev/badge/skills/zhmxiaowo/opencode-simple/eval-harness/github.svg)](https://agentmods.dev/skills/zhmxiaowo/opencode-simple/eval-harness)
Your own site
<a href="https://agentmods.dev/skills/zhmxiaowo/opencode-simple/eval-harness"><img src="https://agentmods.dev/badge/skills/zhmxiaowo/opencode-simple/eval-harness/github.svg" alt="Measured on agentmods" height="20"></a>

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 eval-harness

Your own site · 80×15
<a href="https://agentmods.dev/skills/zhmxiaowo/opencode-simple/eval-harness"><img src="https://agentmods.dev/badge/skills/zhmxiaowo/opencode-simple/eval-harness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,641 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 86% copy Near-identical to another mod 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 $0.00019 $0.01641
Opus 5.5 $0.00008 $0.00656
Sonnet 5.5 $0.00004 $0.00328
Haiku 4.5 $0.00002 $0.00164

Measured 1mo ago against content hash 63166793356d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

eval-harness 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 1mo 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.

Origin

This is a copy

86% identical to eval-harness — 28 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.opencode/skills/eval-harness/SKILL.md · 272 lines

How it starts

The opening of the file, as written. The whole thing — 272 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Eval Harness Skill

A formal evaluation framework for Claude Code sessions, implementing eval-driven development (EDD) principles.

When to Activate

  • Setting up eval-driven development (EDD) for AI-assisted workflows
  • Defining pass/fail criteria for Claude Code task completion
  • Measuring agent reliability with pass@k metrics
  • Creating regression test suites for prompt or agent changes
  • Benchmarking agent performance across model versions

Philosophy

Eval-Driven Development treats evals as the "unit tests of AI development":

  • Define expected behavior BEFORE implementation
  • Run evals continuously during development
  • Track regressions with each change
  • Use pass@k metrics for reliability measurement

Eval Types

Capability Evals

Test if Claude can do something it couldn't before:

[CAPABILITY EVAL: feature-name]
Task: Description of what Claude should accomplish
Success Criteria:
  - [ ] Criterion 1
  - [ ] Criterion 2
  - [ ] Criterion 3
Expected Output: Description of expected result

Regression Evals

Ensure changes don't break existing functionality:

[REGRESSION EVAL: feature-name]
Baseline: SHA or checkpoint name
Tests:
  - existing-test-1: PASS/FAIL
  - existing-test-2: PASS/FAIL
  - existing-test-3: PASS/FAIL
Result: X/Y passed (previously Y/Y)

Grader Types

1. Code-Based Grader

Deterministic checks using code:

# Check if file contains expected pattern
grep -q "export function handleAuth" src/auth.ts && echo "PASS" || echo "FAIL"

# Check if tests pass
npm test -- --testPathPattern="auth" && echo "PASS" || echo "FAIL"

# Check if build succeeds
npm run build && echo "PASS" || echo "FAIL"

2. Model-Based Grader

Use Claude to evaluate open-ended outputs:

[MODEL GRADER PROMPT]
Evaluate the following code change:
1. Does it solve the stated problem?
2. Is it well-structured?
3. Are edge cases handled?
4. Is error handling appropriate?

Score: 1-5 (1=poor, 5=excellent)
Reasoning: [explanation]

Read the full file on GitHub · 272 lines

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. 1mo ago First seen · 272 lines · 19 tokens per session scan A 63166793356d

Subscribe to this mod's changes

eval-harness is a skill published in the GitHub repository zhmxiaowo/opencode-simple (2 stars, last pushed 7mo ago), licensed MIT. It adds 19 tokens to every session and 1,641 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 86% identical to eval-harness, differing in 28 lines, and is treated as a copy.

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