--- name: retellai-rate-limits description: | Implement Retell AI rate limiting, backoff, and idempotency patterns. Use when handling rate limit errors, implementing retry logic, or optimizing API request throughput for Retell AI. Trigger with phrases like "retellai rate limit", "retellai throttling", "retellai 429", "retellai retry", "retellai backoff". allowed-tools: Read, Write, Edit version: 1.0.0 license: MIT author: Jeremy Longshore --- # Retell AI Rate Limits ## Overview Handle Retell AI rate limits gracefully with exponential backoff and idempotency. ## Prerequisites - Retell AI SDK installed - Understanding of async\/await patterns - Access to rate limit headers ## Instructions ### Step 1: Understand Rate Limit Tiers | Tier | Requests\/min | Requests\/day | Burst | |------|-------------|--------------|-------| | Free | 60 | 1,000 | 10 | | Pro | 300 | 10,000 | 50 | | Enterprise | 1,000 | 100,000 | 200 | ### Step 2: Implement Exponential Backoff with Jitter ```typescript async function withExponentialBackoff( operation: () => Promise, config = { maxRetries: 5, baseDelayMs: 1000, maxDelayMs: 32000, jitterMs: 500 } ): Promise { for (let attempt = 0; attempt <= config.maxRetries; attempt++) { try { return await operation(); } catch (error: any) { if (attempt === config.maxRetries) throw error; const status = error.status || error.response?.status; if (status !== 429 && (status < 500 || status >= 600)) throw error; \/\/ Exponential delay with jitter to prevent thundering herd const exponentialDelay = config.baseDelayMs * Math.pow(2, attempt); const jitter = Math.random() * config.jitterMs; const delay = Math.min(exponentialDelay + jitter, config.maxDelayMs); console.log(`Rate limited. Retrying in ${delay.toFixed(0)}ms...`); await new Promise(r => setTimeout(r, delay)); } } throw new Error('Unreachable'); } ``` ### Step 3: Add Idempotency Keys ```typescript import { v4 as uuidv4 } from 'uuid'; import crypto from 'crypto'; \/\/ Generate deterministic key from operation params (for safe retries) function generateIdempotencyKey(operation: string, params: Record): string { const data = JSON.stringify({ operation, params }); return crypto.createHash('sha256').update(data).digest('hex'); } async function idempotentRequest( client: RetellAIClient, params: Record, idempotencyKey?: string \/\/ Pass existing key for retries ): Promise { \/\/ Use provided key (for retries) or generate deterministic key from params const key = idempotencyKey || generateIdempotencyKey(params.method || 'POST', params); return client.request({ ...params, headers: { 'Idempotency-Key': key, ...params.headers }, }); } ``` ## Output - Reliable API calls with automatic retry - Idempotent requests preventing duplicates - Rate limit headers properly handled ## Error Handling | Header | Description | Action | |--------|-------------|--------| | X-RateLimit-Limit | Max requests | Monitor usage | | X-RateLimit-Remaining | Remaining requests | Throttle if low | | X-RateLimit-Reset | Reset timestamp | Wait until reset | | Retry-After | Seconds to wait | Honor this value | ## Examples ### Queue-Based Rate Limiting ```typescript import PQueue from 'p-queue'; const queue = new PQueue({ concurrency: 5, interval: 1000, intervalCap: 10, }); async function queuedRequest(operation: () => Promise): Promise { return queue.add(operation); } ``` ### Monitor Rate Limit Usage ```typescript class RateLimitMonitor { private remaining: number = 60; private resetAt: Date = new Date(); updateFromHeaders(headers: Headers) { this.remaining = parseInt(headers.get('X-RateLimit-Remaining') || '60'); const resetTimestamp = headers.get('X-RateLimit-Reset'); if (resetTimestamp) { this.resetAt = new Date(parseInt(resetTimestamp) * 1000); } } shouldThrottle(): boolean { \/\/ Only throttle if low remaining AND reset hasn't happened yet return this.remaining < 5 && new Date() < this.resetAt; } getWaitTime(): number { return Math.max(0, this.resetAt.getTime() - Date.now()); } } ``` ## Resources - [Retell AI Rate Limits](https:\/\/docs.retellai.com\/rate-limits) - [p-queue Documentation](https:\/\/github.com\/sindresorhus\/p-queue) ## Next Steps For security configuration, see `retellai-security-basics`.