behavior-validator

A black-box testing skill that checks an app, command-line tool, API, or generated file against a written behavior contract without reading its source code. Black-box testing means judging only what users or operators can observe.

In plain words
What is it for?
Use it to write or read a behavior contract, exercise public interfaces, capture observable results, and report each requirement as passed, failed, blocked, or out of scope.
Why use it?
It separates user-visible behavior from implementation details, helping confirm whether the product actually meets its agreed requirements.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/openclaw/agent-skills/behavior-validator
Any agent
npx skills add openclaw/agent-skills --skill behavior-validator
Clone the repo
git clone --depth 1 https://github.com/openclaw/agent-skills

Made for: Claude Code, Codex.

Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 743 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
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 $0.00026 $0.00743
Opus 5 $0.00013 $0.00371
Sonnet 5 $0.00005 $0.00149
Haiku 4.5 $0.00003 $0.00074

Measured 3d ago against content hash 481904b1ffe6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

behavior-validator scanned grade B with 1 finding 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 3d 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.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

chmod 700 "$validator_dir"
skills/behavior-validator/SKILL.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Behavior Validator

Validate observable behavior without inspecting source. Use this as the black-box companion to code-aware review: autoreview judges the change bundle, while behavior-validator judges the running product, CLI, API, or generated artifact against a behavior contract.

Contract

  • Read the behavior contract first. If none exists, write a short one from the user request before testing. See references/contract-template.md.
  • Stay source-blind. Do not inspect source files, diffs, tests, git history, implementation notes, build internals, or review bundles.
  • Interact only through user-visible or operator-visible surfaces: browser, CLI, API, generated files, public logs, screenshots, accessibility trees, or documented runtime output.
  • Treat implementation-looking evidence as contamination. If source access is required to continue, stop and report blocked_source_required.
  • Report findings against contract clauses and observable steps, not code locations.
  • Do not mark a workflow as passing until each relevant contract clause is pass, fail, blocked, or out of scope.

Isolation

Prefer a source-blind workspace:

validator_dir="$(mktemp -d "${TMPDIR:-/tmp}/behavior-validator-run.XXXXXX")"
chmod 700 "$validator_dir"
cp behavior-contract.md "$validator_dir/"
cd "$validator_dir"

Launch or connect to the target from the contract. Keep only the contract, allowed fixtures, and redacted captured evidence in the private validator workspace. Supply credentials through approved secret tooling or exact environment variables; never copy credential values into the workspace, report, screenshots, or logs. Do not use fixed shared paths for contracts or captured evidence. If the app must be started from the source checkout, start it from a separate terminal and do not read source while validating.

Workflow

  1. Parse the contract into user tasks, expected behavior, anti-cheat probes, setup, and evidence requirements.
  2. Prepare runtime access: target URL, CLI command, API endpoint, fixture data, credentials, or generated artifact path.
  3. Exercise each user task as a real user or operator would.
  4. Run anti-cheat probes: vary fixture data, refresh/retry, test empty and invalid inputs, verify persistence, inspect generated output, and confirm buttons/commands perform real work rather than only displaying success text.
  5. Capture evidence as compact redacted notes, screenshots, terminal excerpts, response summaries, file summaries, or accessibility observations. Omit credentials, tokens, cookies, private user data, and unrelated log content.
  6. Emit a structured report. Use references/report-schema.md when a machine-readable report is useful.
  7. If the orchestrator fixes a finding, rerun only the affected contract clauses plus any nearby regression probes.

Read the full file on GitHub · 59 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. 3d ago First seen · 59 lines · 26 tokens per session scan B 481904b1ffe6

Subscribe to this mod's changes

behavior-validator is a skill published in the GitHub repository openclaw/agent-skills (1,070 stars, last pushed 3d ago), licensed MIT. It adds 26 tokens to every session and 743 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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