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/github/spec-kit-copilot/speckit-extensionnpx skills add github/spec-kit-copilot --skill speckit-extensiongit clone --depth 1 https://github.com/github/spec-kit-copilotWhat 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 | $0.00083 | $0.00648 |
| Opus 5 | $0.00042 | $0.00324 |
| Sonnet 5 | $0.00017 | $0.00130 |
| Haiku 4.5 | $0.00008 | $0.00065 |
Grade A, and why
speckit-extension 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 2d 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 — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spec Kit — extensions
Manage spec-kit extensions with the Specify CLI specify extension command
group. Extensions add reusable commands/hooks to a spec-kit project.
Prerequisite: needs the
specifyCLI. Ifspecify --versionfails, install it with the speckit-cli-setup skill first.
When to use
- Find, install, update, or remove a spec-kit extension.
- Temporarily enable/disable an extension or adjust its resolution priority.
- Add or manage extension catalog sources.
How to invoke
# Discover
specify extension list
specify extension search <query>
specify extension info <name>
# Install
specify extension add <name>
specify extension add <name> --force # overwrite if already installed
specify extension add <path> --dev # install from a local directory
specify extension add <name> --from <url> # install from a custom URL
specify extension add <name> --priority <n> # lower number = higher precedence
# Lifecycle
specify extension update [<name>] # update one or all extensions
specify extension enable <name>
specify extension disable <name>
specify extension set-priority <name> <n>
specify extension remove <name>
# Catalogs (sources extensions are resolved from)
specify extension catalog list
specify extension catalog add <https-url> --name <name> [--install-allowed] [--priority <n>] [--description <text>]
specify extension catalog remove <name>
Extension catalog URLs must use HTTPS. New catalogs are not install-allowed by default — pass
--install-allowedto permit installing extensions from them.
Notes
- Resolution priority: lower number = higher precedence (default
10). - Prefer
specify extension searchfirst so you install the correct extension ID. --devis for local development of an extension; point it at the extension's source directory.- When the project was initialized in skills mode (see the speckit-init skill),
an installed extension's commands land as
.github/skills/speckit-<cmd>/SKILL.md. To make Copilot pick up the new skills in the current session, run/skills reload(no restart needed). They are also loaded automatically on the next session start.
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.
- 2d ago First seen · 63 lines · 83 tokens per session scan A aba1330e6128
speckit-extension is a skill published in the GitHub repository github/spec-kit-copilot (11 stars, last pushed 6d ago), licensed MIT. It adds 83 tokens to every session and 648 once invoked, about $0.0004 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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