ai-vision-mcp: Skill for Claude Code

.claude/skills/rbac-permissions-builder/SKILL.md

rbac-permissions-builder is a skill for Claude Code from tan-yong-sheng/ai-vision-mcp. It costs 61 tokens per session (918 once invoked), scanned A, original, MIT.

A builder for role-based access control, a way to decide what users can do based on roles such as user, moderator, or administrator.

In plain words
What is it for?
It helps define permissions and roles, protect server routes, check access in code, show permission hints in the interface, and suggest related tests.
Why use it?
It prevents people from reaching data or actions they are not allowed to use.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is tan-yong-sheng/ai-vision-mcp's own configuration. It tells Claude Code how to work on ai-vision-mcp itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything ai-vision-mcp configures →

Part of the ai-vision-mcp plugin — 29 skills, 1 plugin shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to tan-yong-sheng/ai-vision-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/tan-yong-sheng/ai-vision-mcp/main/.claude/skills/rbac-permissions-builder/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/tan-yong-sheng/ai-vision-mcp

Made for: Claude Code.

Or install ai-vision-mcp, the plugin that ships this one along with the rest of its 29 skills, 1 plugin.

Wrote 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.

agentmods badge for rbac-permissions-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder/github.svg)](https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder)
Your own site
<a href="https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder"><img src="https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder/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.

agentmods 80×15 button for rbac-permissions-builder

Your own site · 80×15
<a href="https://agentmods.dev/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder"><img src="https://agentmods.dev/badge/skills/tan-yong-sheng/ai-vision-mcp/rbac-permissions-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 918 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00061 $0.00918
Opus 5 $0.00030 $0.00459
Sonnet 5 $0.00012 $0.00184
Haiku 4.5 $0.00006 $0.00092

Measured 13d ago against content hash e43a2fece53b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

rbac-permissions-builder 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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

.claude/skills/rbac-permissions-builder/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

RBAC/Permissions Builder

Implement flexible role-based access control systems.

Permission Matrix

// Define permissions
export enum Permission {
  USER_READ = "user:read",
  USER_WRITE = "user:write",
  USER_DELETE = "user:delete",
  POST_READ = "post:read",
  POST_WRITE = "post:write",
  ADMIN_ACCESS = "admin:access",
}

// Define roles
export const ROLE_PERMISSIONS = {
  user: [Permission.USER_READ, Permission.POST_READ, Permission.POST_WRITE],
  moderator: [...userPermissions, Permission.POST_DELETE],
  admin: Object.values(Permission), // All permissions
};

// Check permission
export const hasPermission = (user: User, permission: Permission): boolean => {
  return ROLE_PERMISSIONS[user.role]?.includes(permission) ?? false;
};

Route Guards (Express)

export const requirePermission = (...permissions: Permission[]) => {
  return (req: Request, res: Response, next: NextFunction) => {
    if (!req.user) {
      return res.status(401).json({ error: "Unauthorized" });
    }

    const hasAllPermissions = permissions.every((p) =>
      hasPermission(req.user, p)
    );

    if (!hasAllPermissions) {
      return res.status(403).json({ error: "Forbidden" });
    }

    next();
  };
};

// Usage
router.delete(
  "/users/:id",
  authenticate,
  requirePermission(Permission.USER_DELETE),
  controller.delete
);

Policy Pattern

// policies/user.policy.ts
export class UserPolicy {
  static canUpdate(currentUser: User, targetUser: User): boolean {
    // Users can update themselves
    if (currentUser.id === targetUser.id) return true;

    // Admins can update anyone
    if (hasPermission(currentUser, Permission.USER_WRITE)) return true;

    return false;
  }

  static canDelete(currentUser: User, targetUser: User): boolean {
    // Can't delete yourself
    if (currentUser.id === targetUser.id) return false;

    // Only admins can delete
    return hasPermission(currentUser, Permission.USER_DELETE);
  }
}

// Usage in controller
if (!UserPolicy.canUpdate(req.user, targetUser)) {
  return res.status(403).json({ error: "Cannot update this user" });
}

Read the full file on GitHub · 158 lines

Changes

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.

  1. 13d ago First seen · 158 lines · 61 tokens per session scan A e43a2fece53b

Subscribe to this mod's changes

rbac-permissions-builder is a skill published in the GitHub repository tan-yong-sheng/ai-vision-mcp (78 stars, last pushed 5mo ago), licensed MIT. It adds 61 tokens to every session and 918 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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