MCP Structured Output バリデーター

コーディング中級

outputSchemaを宣言してツール出力を自動検証し、人間が読めるcontentと機械がパースできるstructuredContentを同時提供します。

トリガー/mcp-output-schema

使用頻度per tool

MCP Server Authorなら？ Use /mcp-output-schema to add type-safe outputs to your tools

Integration Developerなら？ Ensure downstream systems can parse tool results reliably

MCPStructured OutputJSON Schemaバリデーション

動作フロー

/mcp-output-schema [tool-name] run

↓

Phase 1: analyze tool output

output-analysis

Infer schema from current tool responses

schema-gen

Generate outputSchema definition

validator

Create runtime validation layer

↓

Wire schema into tool definition

↓

✓ Tool with outputSchema + structuredContent validation

スキルコード

# MCP Structured Output Validator
## Trigger: /mcp-output-schema [tool-name]

When invoked:

1. Define outputSchema on tool registration:
```typescript
server.tool(
  "get-weather",
  {
    description: "Get current weather for a city",
    inputSchema: {
      type: "object",
      properties: {
        city: { type: "string" }
      },
      required: ["city"]
    },
    // NEW: declare structured output schema
    outputSchema: {
      type: "object",
      properties: {
        temperature: { type: "number" },
        unit: { type: "string", enum: ["celsius", "fahrenheit"] },
        condition: { type: "string" },
        humidity: { type: "number" }
      },
      required: ["temperature", "unit", "condition"]
    }
  },
  async ({ city }) => {
    const data = await fetchWeather(city);
    return {
      // Human-readable content (always present)
      content: [{
        type: "text",
        text: `It's ${data.temp}°C and ${data.condition} in ${city}`
      }],
      // Machine-readable structured output (validated against outputSchema)
      structuredContent: {
        temperature: data.temp,
        unit: "celsius",
        condition: data.condition,
        humidity: data.humidity
      }
    };
  }
);
```

2. Validation behavior:
 - Server SDK auto-validates structuredContent against outputSchema
 - Schema violations throw at runtime (fail-fast)
 - structuredContent MUST be present when outputSchema is defined
 - content[] is still required for human-readable fallback

3. Client consumption:
```typescript
const result = await client.callTool("get-weather", { city: "Seoul" });
// Type-safe access to structured data
const temp = result.structuredContent.temperature; // number
const condition = result.structuredContent.condition; // string
```

コピーしてCLAUDE.mdに貼り付ければ、すぐに使えます。