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 skills add AlexTeplovCPA/it-contractors-skills --skill checking-gst-hstgit clone --depth 1 https://github.com/AlexTeplovCPA/it-contractors-skillsWrote 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/alexteplovcpa/it-contractors-skills/checking-gst-hst)<a href="https://agentmods.dev/skills/alexteplovcpa/it-contractors-skills/checking-gst-hst"><img src="https://agentmods.dev/badge/skills/alexteplovcpa/it-contractors-skills/checking-gst-hst/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/alexteplovcpa/it-contractors-skills/checking-gst-hst"><img src="https://agentmods.dev/badge/skills/alexteplovcpa/it-contractors-skills/checking-gst-hst.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 | $0.00097 | $0.01413 |
| Opus 5 | $0.00048 | $0.00707 |
| Sonnet 5 | $0.00019 | $0.00283 |
| Haiku 4.5 | $0.00010 | $0.00141 |
Grade A, and why
checking-gst-hst 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 11d 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 — 163 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Checking GST/HST
Review GST/HST registration, collection, and input tax credit facts for a Canadian IT contractor.
Core Rules
- Organize and flag GST/HST facts, do not advise on compliance positions.
- Do not determine final registration obligation.
- Do not calculate net tax owing.
- Do not determine final ITC eligibility.
- Do not determine the correct GST/HST rate for any supply.
- Preserve uncertainty where facts are incomplete.
- Do not state that the user is or is not required to register.
- Do not state that the user's GST/HST return is correct.
- Do not state that the user is ready to file.
- Use this phrase where relevant: "That is outside what this workflow covers. It is a question for a CPA before you file."
Inputs
Do not ask the user to share SIN, business number, account numbers, or client names. Use general descriptions and rounded amounts.
Accept any of:
- output from
identifying-income-sources - output from
organizing-t2125-gross-business-income - prior year GST/HST return summary
- invoice summaries or client contract descriptions
- expense records for ITC purposes
- user explanation in chat
Minimum useful input:
- some indication of annual business revenue
- description of the type of services provided
- any known GST/HST registration details
Read from the shared input schema where available: case_id, tax_year, engagement_mode, user_profile, facts.business_activity, facts.gst_hst, documents.gst_hst_records, form_context, review_state.
Read from prior skill outputs where available: identifying-income-sources, organizing-t2125-gross-business-income.
Workflow
1. Confirm GST/HST review is relevant
Check whether the user earns income from a business activity in Canada. If income appears entirely employment income or exempt, note this and return an appropriate status.
2. Organize registration facts
Identify:
- whether the user is currently registered for GST/HST
- whether the user has a GST/HST number
- approximate annual revenue across all business income sources
- whether any income may be from zero-rated or exempt supplies
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.
- 11d ago First seen · 163 lines · 97 tokens per session scan A 8f40e1c36fb6
checking-gst-hst is a skill published in the GitHub repository AlexTeplovCPA/it-contractors-skills (2 stars, last pushed 2mo ago), licensed MIT. It adds 97 tokens to every session and 1,413 once invoked, about $0.0005 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 2026-08-31.
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