Agent Harness Design
Use when designing tool definitions for a new agent or subagent, an agent shows high retry rates, ambiguous tool invocations, or silent failures, or an existing agent harness needs a quality review.
Install
$ agentstack add skill-yeaight7-agent-powerups-agent-harness-design ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-yeaight7-agent-powerups-agent-harness-design) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
Agent Harness Design
Use when designing or improving how an agent invokes tools, handles errors, and decides when to stop.
Tool Design Rules
- Names: explicit and stable (
read_file,run_tests); no generic names (do_action,execute) - Schemas: required fields only; enum values for modes; reject invalid input with a clear error
- Output: always include
status(success/warning/error),summary,next_actions,artifacts - Catch-all tools: avoid
run_bash/shell_execunless task is genuinely open-ended; add allowlist
Error Path Rules
| Case | Required response | |------|------------------| | Invalid input | Reject immediately with exact field name | | Transient failure | Include retry_after hint and idempotency note | | Non-recoverable | Set stop: true, describe manual resolution |
Retry and Stop Conditions
Define in harness, not inside tools:
- Max retries: 2
- Hard stops:
status: "error"withstop: true; same inputs called twice in a row
Granularity Guide
| Risk | Granularity | |------|------------| | High (deploy, migrate, permissions) | Micro — one action, explicit confirmation | | Medium (edit, read, search) | Standard composite | | Low (format, list, report) | Macro batch acceptable |
Context Budget
- Keep system prompt fixed and minimal
- Load large guidance from skills on demand
- Compact at phase boundaries, not mid-task
Verification
- [ ] Every tool has an explicit, stable name and exactly one distinct operation
- [ ] Schemas use required fields and enums — no free-text mode strings, no behavior-changing optionals
- [ ] Every tool response carries
status,summary,next_actions, andartifacts - [ ] Every tool defines its invalid-input, transient-failure, and non-recoverable paths
- [ ] Retry ceiling and stop conditions are declared in the harness, not inside tools
- [ ] Any catch-all tool is documented with its risk and guarded by an allowlist or preflight check
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: yeaight7
- Source: yeaight7/agent-powerups
- License: Apache-2.0
Install and usage instructions live in the source repository linked above.
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Versions
- v0.1.0 Imported from the upstream source.