api-patterns

A set of development rules for building SmartLead API clients and MCP tools in TypeScript. It describes shared client structure, tool registration, input validation, error handling, retries, and type-safe code.

In plain words
What is it for?
Use it when extending SmartLead API modules, registering MCP tools, validating requests with Zod, handling API errors, or adding retry behavior.
Why use it?
It helps new API code follow the same patterns as the existing SmartLead MCP Server instead of introducing inconsistent approaches.

Cursor rule for Cursor

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.

agentmods
npx agentmods add rules/leadmagic/smartlead-mcp-server/api-patterns
Clone the repo
git clone --depth 1 https://github.com/LeadMagic/smartlead-mcp-server

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 3,222 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.03222
Opus 5 $0.00000 $0.01611
Sonnet 5 $0.00000 $0.00644
Haiku 4.5 $0.00000 $0.00322

Measured yesterday against content hash e700f4980bf9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-patterns scanned grade A with 0 findings against 26 rules in 11 categories โ€” prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency โ€” 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.

.cursor/rules/api-patterns.mdc ยท 423 lines

How it starts

The opening of the file, as written. The whole thing โ€” 423 lines โ€” stays where its author put it; the contents beside it link to each section on GitHub.


name: SmartLead MCP API Development Patterns description: Development patterns for API clients and MCP tools in the SmartLead server author: LeadMagic Team version: 1.0.0

๐Ÿ—๏ธ SmartLead API Development Patterns & Best Practices

Developer Guide: Master the patterns and practices used throughout the SmartLead MCP Server. This guide will help you write consistent, maintainable code that follows our established conventions.

๐ŸŽฏ Quick Reference

๐Ÿ”ฅ Most Important Patterns

  1. Base Client Extension โ†’ All API modules extend BaseSmartLeadClient
  2. MCP Tool Registration โ†’ Use the standard registration pattern
  3. Zod Schema Validation โ†’ All inputs validated with Zod
  4. Error Handling โ†’ Use SmartLeadError for API errors
  5. Type Safety โ†’ Avoid any, use proper TypeScript types

๐Ÿ—๏ธ SmartLead API Client Architecture

๐Ÿ› ๏ธ Base Client Pattern

File: src/client/base.ts

The foundation of all API interactions:

export abstract class BaseSmartLeadClient {
  protected config: SmartLeadConfig;
  
  constructor(config: SmartLeadConfig) {
    this.config = config;
  }
  
  // ๐Ÿ”„ Automatic retry with exponential backoff
  protected async withRetry<T>(operation: () => Promise<T>): Promise<T> {
    // Handles transient failures automatically
  }
  
  // ๐ŸŒ HTTP methods with proper typing
  protected async get<T>(url: string): Promise<T> { }
  protected async post<T>(url: string, data: unknown): Promise<T> { }
  protected async put<T>(url: string, data: unknown): Promise<T> { }
  protected async delete<T>(url: string): Promise<T> { }
}

Key Features:

  • โœ… HTTP request handling with Axios
  • โœ… Automatic retry logic with exponential backoff
  • โœ… Rate limiting and request queuing
  • โœ… Error handling with SmartLeadError class
  • โœ… Request/response logging for debugging

๐Ÿ”Œ Module Structure Pattern

Example: src/modules/campaigns/client.ts

Read the full file on GitHub ยท 423 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. yesterday First seen ยท 423 lines ยท 0 tokens per session scan A e700f4980bf9

Subscribe to this mod's changes

api-patterns is a cursor rule published in the GitHub repository LeadMagic/smartlead-mcp-server (21 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,222 tokens. 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.