leanmcp-builder

1# Leanmcp Builder Skill
2 
3This skill guides you in building MCP servers using the Leanmcp SDK - a decorator-based TypeScript framework for elegant MCP development.
4 
5## When to Use This Skill
6 
7- User asks for "leanmcp server"
8- User wants "MCP with decorators"
9- User needs "authenticated MCP server"
10- User wants "simpler MCP development"
11- User mentions "@leanmcp/core"
12- User needs "user input collection" or "elicitation"
13- User wants "environment injection" for multi-tenant secrets
14 
15## Leanmcp vs Vanilla MCP
16 
17| Feature | Vanilla MCP | Leanmcp SDK |
18|---------|-------------|-------------|
19| Tool definition | Manual schema | `@Tool` decorator with auto-schema |
20| Input validation | Manual | Automatic with `@SchemaConstraint` |
21| Service discovery | Manual registration | Auto-discovery from `./mcp` directory |
22| Authentication | DIY | `@Authenticated` decorator |
23| User input | Not built-in | `@Elicitation` decorator |
24| Secrets | DIY | `@RequireEnv` + `getEnv()` |
25 
26## Core Packages
27 
28```bash
29# Minimal setup
30npm install @leanmcp/core
31 
32# With authentication
33npm install @leanmcp/auth
34 
35# With user input forms
36npm install @leanmcp/elicitation
37 
38# With user secrets
39npm install @leanmcp/env-injection
40 
41# CLI (global or dev)
42npm install -g @leanmcp/cli
43```
44 
45## Project Structure
46 
47```
48my-leanmcp-server/
49├── main.ts                 # Entry point (minimal)
50├── mcp/                    # Auto-discovered services
51│   ├── example/
52│   │   └── index.ts        # Exports ExampleService
53…