Vercel Flags is an SDK for working with feature flags in software applications. The available input does not provide enough information to describe its supported platforms, features, or users.
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 vercel/flags --skill vercel-flagsgit clone --depth 1 https://github.com/vercel/flagsWrote 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/vercel/flags/vercel-flags)<a href="https://agentmods.dev/skills/vercel/flags/vercel-flags"><img src="https://agentmods.dev/badge/skills/vercel/flags/vercel-flags/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/vercel/flags/vercel-flags"><img src="https://agentmods.dev/badge/skills/vercel/flags/vercel-flags.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 | $0.00177 | $0.02700 |
| Opus 5.5 | $0.00071 | $0.01080 |
| Sonnet 5.5 | $0.00035 | $0.00540 |
| Haiku 4.5 | $0.00018 | $0.00270 |
Grade A, and why
vercel-flags 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 yesterday.
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 — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Vercel Flags
Vercel Flags is Vercel's feature flags platform. Flags are created and managed in the Vercel dashboard or with the vercel flags CLI, evaluated server-side in your app, and switched per environment (Development, Preview, Production) without a redeploy.
- Docs: https://vercel.com/docs/flags
- CLI reference: https://vercel.com/docs/cli/flags
Use this skill to decide how a feature should be flagged, to create and change flags, and to run rollouts and experiments. Write app code with the skill that matches the stack (see Choose an approach). Do not leave CLI steps as "next steps" for the user; execute them yourself.
Route the request
- Planning ("put this behind a flag", "roll this out to 10%", "A/B test the pricing page", "add a kill switch"): follow Plan a flag, then Choose an approach.
- Create or manage a flag with no code change (create, inspect, enable, set, split, rollout, rules, archive): follow Manage flags with the CLI. This needs an authenticated CLI, not SDK packages, Toolbar, Flags Explorer, or
.env.local(exceptvercel flags override, which readsFLAGS_SECRET). - Add a flag to an app that already uses the Flags SDK (
flagsinpackage.json): load theflags-sdkskill right away; it creates the flag on Vercel and declares it in code. - Implement in code otherwise: follow Choose an approach and load the matching skill or reference. Inside an app repository, treat an ambiguous request as plan, create, and implement.
Choose an approach
Check the project before writing code.
- Already using another flag provider (Statsig, LaunchDarkly, PostHog, GrowthBook, and so on): keep it. On Next.js or SvelteKit, the Flags SDK connects to it through an adapter; load the
flags-sdkskill. On any other stack, use the provider's own SDK. Rollouts, targeting, and experiments for that provider are configured in its own dashboard, not withvercel flags; the CLI and lifecycle sections of this skill do not apply. - No provider yet: use Vercel Flags. Pick the integration by stack (SDKs):
- Next.js or SvelteKit: the Flags SDK (
flags+@flags-sdk/vercel). It adds Flags Explorer integration and precompute for static pages. Load theflags-sdkskill. If it is not available, suggestnpx skills add vercel/flags@flags-sdk(do not auto-install). - Any other framework or a plain server (for example Express):
@vercel/flags-core. See Other frameworks. - The user wants provider portability or already uses OpenFeature: the Vercel Flags OpenFeature provider (Using OpenFeature with Vercel Flags).
- Next.js or SvelteKit: the Flags SDK (
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.
- yesterday Changed 40e0a15fcc92
- 6d ago First seen · 116 lines · 177 tokens per session scan A b1164dd4ed28
vercel-flags is a skill published in the GitHub repository vercel/flags (625 stars, last pushed today), licensed MIT. It adds 177 tokens to every session and 2,700 once invoked, about $0.0007 per session on Opus 5.5. 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 2026-10-17.
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