api-design

Install

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.

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.

Security

Grade A, and why

api-design 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.

.cursor/rules/api-design.mdc · 43 lines

What it actually says

import { NextResponse } from 'next/server'
import { createServerClient } from '@supabase/ssr'

export async function GET(request: Request, { params }: { params: Promise<{ id: string }> }) {
  const { id } = await params
  const supabase = createServerClient(...)
  
  const { data: { user } } = await supabase.auth.getUser()
  if (!user) {
    return NextResponse.json(
      { data: null, error: { code: 'UNAUTHORIZED', message: 'Login required' } }, 
      { status: 401 }
    )
  }
  
  // ... fetch data
  return NextResponse.json({ data: { id, status: 'ok' }, error: null })
}

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.

Related

Other cursor rules, from other repositories