Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/itallstartedwithaidea/agent-skillsnpx agentmods add skills/itallstartedwithaidea/agent-skills/multi-harness-portabilityWrote 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.
[](https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/multi-harness-portability)<a href="https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/multi-harness-portability"><img src="https://agentmods.dev/badge/skills/itallstartedwithaidea/agent-skills/multi-harness-portability/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.
<a href="https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/multi-harness-portability"><img src="https://agentmods.dev/badge/skills/itallstartedwithaidea/agent-skills/multi-harness-portability.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00050 | $0.02377 |
| Opus 5.5 | $0.00020 | $0.00951 |
| Sonnet 5.5 | $0.00010 | $0.00475 |
| Haiku 4.5 | $0.00005 | $0.00238 |
Grade A, and why
multi-harness-portability 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.
How it starts
The opening of the file, as written. The whole thing — 238 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Multi-Harness Portability
Part of Agent Skills™ by googleadsagent.ai™
Description
Multi-Harness Portability is the engineering discipline of writing agent skills, prompts, and configurations that work across every major AI coding harness — Claude Code, Cursor, Codex, Gemini CLI, OpenCode, and beyond. The AI tooling landscape is fragmenting rapidly: teams use different editors, different CLI tools, different models. Skills that are locked to a single platform become liabilities; skills that are portable become assets that compound in value across the entire organization.
This skill encodes the portability architecture developed for Agent Skills™ by googleadsagent.ai™, where every skill in the repository is designed to function across all major harnesses. The key insight is that portability is an architectural decision, not an afterthought. It requires abstraction layers that map platform-specific capabilities (hooks, rules, instructions, system prompts) to a universal skill interface, with platform-specific adapters handling the translation.
The portability layer handles three categories of platform differences: skill loading (how the skill enters the agent's context), tool access (what tools are available and how they're invoked), and output formatting (how the agent delivers results). Each category requires its own adapter pattern, and the combination provides true write-once-run-anywhere agent skills.
Use When
- Your team uses multiple AI coding tools (Claude Code, Cursor, Codex, etc.)
- You want to maintain a single skill repository that serves all platforms
- Skills developed for one platform need to be ported to others
- You are building an open-source skill library for the community
- CI/CD pipelines need to validate skills across multiple platforms
- Organization policy requires platform-agnostic tooling
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.
- 1mo ago First seen · 238 lines · 50 tokens per session scan A 85916b5211ec
multi-harness-portability is a skill published in the GitHub repository itallstartedwithaidea/agent-skills (44 stars, last pushed 6mo ago), licensed MIT. It adds 50 tokens to every session and 2,377 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.
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