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.
npx agentmods add skills/t2a-protocol/t2a/t2a-tool-authornpx skills add t2a-protocol/T2A --skill t2a-tool-authorgit clone --depth 1 https://github.com/t2a-protocol/T2AWrote 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/t2a-protocol/t2a/t2a-tool-author)<a href="https://agentmods.dev/skills/t2a-protocol/t2a/t2a-tool-author"><img src="https://agentmods.dev/badge/skills/t2a-protocol/t2a/t2a-tool-author.svg" alt="Measured on agentmods" 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 | $0.00049 | $0.00493 |
| Opus 5 | $0.00024 | $0.00246 |
| Sonnet 5 | $0.00010 | $0.00099 |
| Haiku 4.5 | $0.00005 | $0.00049 |
Grade A, and why
t2a-tool-author 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 6d 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.
What it actually says
T2A Tool Author
Instructions
Use this skill when changing a tool to support T2A.
- Find one bounded reasoning checkpoint.
- Replace one embedded model call with a local T2A handoff.
- Keep the rest of the tool unchanged.
- Create a capsule with
task.json,prompt.md, bounded input, andoutput.schema.json. - Return a T2A Handoff Result with
type: "t2a.handoff". - Accept host-agent-written
output.json. - Run T2A protocol validation and tool-owned domain validation before commit/resume.
- Add a demo fixture or template task and run
t2a validate.
Before commit/resume, check:
- protocol validation passed
validation.jsonmatches the current task- domain validation passed
- only then mutate state
Before editing, inspect the tool and propose:
- the checkpoint to migrate
- files to change
- files to add
- validation command
- risks / assumptions
Wait for approval unless the user explicitly asked you to proceed.
Guidelines
- Do not add OpenAI, Anthropic, Gemini, Ollama, LangChain, or other LLM SDKs.
- Do not add new
model,provider,base_url,api_key, or provider config for the migrated T2A path. - Do not remove unrelated existing provider configuration unless it belongs to the checkpoint being migrated and the user approves.
- Do not build an agent framework, scheduler, daemon, queue, or MCP bridge.
- Do not refactor the whole tool.
- Do not skip
output.schema.json. - Do not let the host agent directly mutate tool state.
- Do not trust
output.jsonwithout validation. - Do not auto-resume before validation.
- A first migration demo fixture may be generated and test-only.
Examples
- Replace a summarization provider call with a capsule and
output.schema.json. - Replace issue triage model config with a local
t2a.handoff. - Replace risk classification model calls with host-agent reasoning and tool-owned ID validation.
What ships with it
1 file 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.
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.
- 6d ago First seen · 56 lines · 49 tokens per session scan A f4a576d59411
t2a-tool-author is a skill published in the GitHub repository t2a-protocol/T2A (48 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 49 tokens to every session and 493 once invoked, about $0.0002 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 2026-08-30.
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