Build MCP (Model Context Protocol) servers including tool definition, schema design, authentication, error handling, and Claude Code integration.
SkillScore83Maintained
Automatic
◆AI Engineer pack
Last verified 8/28/2026
What it changes
Passed 19 of 23 test cases with the skill, and 14 of 23 without it.
Without skill61%
With skill83%
Checks it passed that the model alone missed
Includes the section heading `## Data Source`.
Formats the Data Source section using bullet points.
Uses `# MCP Server Spec:` as the top-level heading format.
and 6 more in the full report
6 fixed13 passed either way3 still failing1 broke
Pass-rate lift
+22 pp
Tokens
+19%
Agent turns
0%
Response time
-26%
Model gemini-3.6-flashMeasured 8/28/2026v119 of 23 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 6 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 6
Prompt
I need to configure `.mcp.json` for a server that connects to a remote API requiring an API key `sk_live_123456789`. Write out the complete `.mcp.json` block showing how to pass this key safely.
What was checked, without and with the skill
Checked
Without skill
With skill
Uses environment variable syntax like `${API_KEY}` inside the `.mcp.json` configuration.
Passed
Passed
Omits literal secret string `sk_live_123456789` from the configuration output.
Missed
Passed
case-09 · gemini-3.6-flash · 8/28/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md151 lines3 files
MCP Server Development
Framework
IRON LAW: Tools Must Be Self-Describing
Every MCP tool must have a clear name, description, and input schema
that allows the AI model to understand WHEN and HOW to use it without
any external documentation. If the model can't figure out when to call
your tool from its name and description alone, the tool is poorly designed.
MCP Architecture
Claude Code / AI Agent
↓ (stdio JSON-RPC 2.0)
MCP Server (your code)
↓
Your Data Source (DB, API, file system, etc.)
Protocol Basics
Concept
What It Is
Transport
stdio (stdin/stdout) — most common for local servers
Protocol
JSON-RPC 2.0
Tools
Functions the model can call (read data, take actions)
Resources
Data the model can read (files, database records)
Prompts
Pre-built prompt templates the model can use
Tool Design Principles
Atomic operations: Each tool does ONE thing. "search_users" not "search_and_update_users"
Build Model Context Protocol (MCP) servers that expose tools, resources, and prompts to AI agents. Use when asked to create an MCP server, add new tools to an existing MCP, or integrate external APIs as MCP tools.
Choose the right e-commerce platform mix for a Taiwan business — DTC platforms (Shopline, 91APP, Shopify), marketplaces (Shopee, momo, PChome), or hybrid. Use when comparing platform fees, traffic potential, brand control trade-offs, or designing a go-to-market channel strategy for Taiwan. Do NOT use for specific platform integration details (see platform-specific skills). STATUS: SKELETON — body pending.