Vellum Assistant is a personal AI assistant that remembers information about users, learns their preferences, and takes actions across connected apps. It is intended for people who want an assistant that can manage conversations, unfinished work, and proactive notifications over time. The catalogue skills, hooks, instruction, and setting configure or extend how the assistant works.
Borrowing it
Nothing to install: this file belongs to vellum-ai/vellum-assistant. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/vellum-ai/vellum-assistant/main/.cursor/skills/vellum-skill-authoring/SKILL.mdgit clone --depth 1 https://github.com/vellum-ai/vellum-assistantWrote 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/vellum-ai/vellum-assistant/vellum-skill-authoring)<a href="https://agentmods.dev/skills/vellum-ai/vellum-assistant/vellum-skill-authoring"><img src="https://agentmods.dev/badge/skills/vellum-ai/vellum-assistant/vellum-skill-authoring/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/vellum-ai/vellum-assistant/vellum-skill-authoring"><img src="https://agentmods.dev/badge/skills/vellum-ai/vellum-assistant/vellum-skill-authoring.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00051 | $0.00381 |
| Opus 5 | $0.00026 | $0.00191 |
| Sonnet 5 | $0.00010 | $0.00076 |
| Haiku 4.5 | $0.00005 | $0.00038 |
Grade A, and why
vellum-skill-authoring 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 13d 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
Vellum Skill Authoring
Scope
Use this for Vellum runtime skills in skills/ and bundled assistant skills, not for Cursor Agent Skills under .cursor/skills/.
Core Constraints
- First-party skills must be portable and isolated.
skills/must not import fromassistant/.assistant/must not import fromskills/.- Prefer skill processes and supported contracts over new daemon tool registrations.
- Avoid secrets, real personal data, and machine-specific paths in skill docs, tests, and fixtures.
SKILL.md Quality Bar
Skill instructions should be concise and operational:
- State what the skill does and when to use it.
- Prefer concrete steps over broad advice.
- Keep user-facing terminology consistent.
- Use generic examples only.
- Avoid requiring hidden local state unless setup instructions create it.
Tool And Script Review
When a skill adds scripts or tools:
- Verify tool input/output contracts are explicit.
- Check error handling and user-facing messages.
- Confirm scripts can run in the skill process environment.
- Avoid direct imports across isolation boundaries.
- Add focused tests for parsing, contract handling, and failure cases.
Catalog And Packaging
When adding or renaming skills, check the relevant catalog, manifest, bundled registry, or packaging path used by the runtime. Do not assume a SKILL.md file alone makes the skill available to users.
Verification
Use focused tests around the changed skill, catalog entry, proxy bridge, or bundled registry. Add typecheck when contracts or generated manifests changed.
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.
- 13d ago First seen · 47 lines · 51 tokens per session scan A 3c8e1f7f8d13
vellum-skill-authoring is a skill published in the GitHub repository vellum-ai/vellum-assistant (1,234 stars, last pushed today), licensed MIT. It adds 51 tokens to every session and 381 once invoked, about $0.0003 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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