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/AGENTS.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/instructions/vellum-ai/vellum-assistant/agents-md)<a href="https://agentmods.dev/instructions/vellum-ai/vellum-assistant/agents-md"><img src="https://agentmods.dev/badge/instructions/vellum-ai/vellum-assistant/agents-md.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 | $0.09582 | $0.09582 |
| Opus 5 | $0.04791 | $0.04791 |
| Sonnet 5 | $0.01916 | $0.01916 |
| Haiku 4.5 | $0.00958 | $0.00958 |
Grade A, and why
vellum-assistant AGENTS.md scanned grade A with 1 finding 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 5d 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.
Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
- **Windows subprocesses**: Every subprocess that can run inside the packaged Windows client, local assistant, first-party skills, or `clients/windows` tooling must set `windowsHide: true`. This applies to Node child pro How it starts
The opening of the file, as written. The whole thing — 365 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Vellum Assistant — Agent Instructions
Project Structure
Bun + TypeScript monorepo with multiple packages:
clients/: End-user app surfaces:clients/web/(Vite + React Router v7 SPA),clients/ios/(Capacitor iOS shell that loads the web app in a WKWebView),clients/android/(Capacitor Android shell that loads the web app in a WebView),clients/macos/(Electron desktop shell that wrapsclients/web/; daemon/gateway lifecycle is owned by thevellumCLI, which the app invokes as a subprocess; auto-update viaelectron-updater; CI workflows arepr-macos.yaml/ci-main-macos.yaml),clients/linux/(Electron desktop shell aroundclients/web/packaged as an AppImage; CI workflows arepr-linux.yaml/ci-main-linux.yaml),clients/windows/(Electron desktop shell aroundclients/web/at capability parity with macOS, seeclients/windows/docs/parity-matrix.md; CI workflows arepr-windows.yaml/ci-main-windows.yaml), andclients/chrome-extension/(MV3 Chrome browser extension). Seeclients/README.mdandclients/AGENTS.md.assistant/— Main backend service (Bun + TypeScript)cli/— Multi-assistant management CLI (Bun + TypeScript). Seecli/AGENTS.md.gateway/— Channel ingress gateway (Bun + TypeScript)packages/— Shared internal packages (e.g.service-contractsfor CES wire-protocol schemas)scripts/— Utility scriptsskills/— First-party skill catalog (portable skill packages). Seeskills/AGENTS.mdfor contribution rules and portability requirements..claude/— Claude Code slash commands and helper scripts (see.claude/README.md). Most commands are shared fromclaude-skillsvia symlinks; repo-local commands (/update,/release) live in.claude/skills/<name>/as local skill directories. The/updatecommand usesvellum ps,vellum sleep, andvellum waketo manage assistant lifecycle.- Evals have moved to a dedicated repo: vellum-ai/evals.
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.
- 5d ago Changed · +41 tokens per session d65e82cd273b
- 6d ago Changed · +26 tokens per session f1432ffe6a08
- 9d ago First seen · 365 lines · 9,515 tokens per session scan A 7e870568d28b
vellum-assistant AGENTS.md is an instructions file published in the GitHub repository vellum-ai/vellum-assistant (1,204 stars, last pushed today), licensed MIT. It adds 9,582 tokens to every session, about $0.0479 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.