mcp-builder
MCP (Model Context Protocol) server building principles. Tool design, resource patterns, best practices.
40
Quality
27%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
Securityby
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./.agent/skills/mcp-builder/SKILL.mdMCP Builder
Principles for building MCP servers.
1. MCP Overview
What is MCP?
Model Context Protocol - standard for connecting AI systems with external tools and data sources.
Core Concepts
| Concept | Purpose |
|---|---|
| Tools | Functions AI can call |
| Resources | Data AI can read |
| Prompts | Pre-defined prompt templates |
2. Server Architecture
Project Structure
my-mcp-server/
├── src/
│ └── index.ts # Main entry
├── package.json
└── tsconfig.jsonTransport Types
| Type | Use |
|---|---|
| Stdio | Local, CLI-based |
| SSE | Web-based, streaming |
| WebSocket | Real-time, bidirectional |
3. Tool Design Principles
Good Tool Design
| Principle | Description |
|---|---|
| Clear name | Action-oriented (get_weather, create_user) |
| Single purpose | One thing well |
| Validated input | Schema with types and descriptions |
| Structured output | Predictable response format |
Input Schema Design
| Field | Required? |
|---|---|
| Type | Yes - object |
| Properties | Define each param |
| Required | List mandatory params |
| Description | Human-readable |
4. Resource Patterns
Resource Types
| Type | Use |
|---|---|
| Static | Fixed data (config, docs) |
| Dynamic | Generated on request |
| Template | URI with parameters |
URI Patterns
| Pattern | Example |
|---|---|
| Fixed | docs://readme |
| Parameterized | users://{userId} |
| Collection | files://project/* |
5. Error Handling
Error Types
| Situation | Response |
|---|---|
| Invalid params | Validation error message |
| Not found | Clear "not found" |
| Server error | Generic error, log details |
Best Practices
- Return structured errors
- Don't expose internal details
- Log for debugging
- Provide actionable messages
6. Multimodal Handling
Supported Types
| Type | Encoding |
|---|---|
| Text | Plain text |
| Images | Base64 + MIME type |
| Files | Base64 + MIME type |
7. Security Principles
Input Validation
- Validate all tool inputs
- Sanitize user-provided data
- Limit resource access
API Keys
- Use environment variables
- Don't log secrets
- Validate permissions
8. Configuration
Claude Desktop Config
| Field | Purpose |
|---|---|
| command | Executable to run |
| args | Command arguments |
| env | Environment variables |
9. Testing
Test Categories
| Type | Focus |
|---|---|
| Unit | Tool logic |
| Integration | Full server |
| Contract | Schema validation |
10. Best Practices Checklist
- Clear, action-oriented tool names
- Complete input schemas with descriptions
- Structured JSON output
- Error handling for all cases
- Input validation
- Environment-based configuration
- Logging for debugging
Remember: MCP tools should be simple, focused, and well-documented. The AI relies on descriptions to use them correctly.
- Repository
- lchenrique/politron-ide
- Commit
7114206
- Last updated
- Created
Is this your skill?
If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.