MCP JSON Schema Validation 是什么？

JSON Schema 验证 —— 给 MCP 工具穿上"数据校验盔甲"，防止垃圾进垃圾出

📝 JSON Schema 基础

工具定义示例

// MCP 工具的 JSON Schema 定义
{
  "name": "web_search",
  "description": "搜索网页",
  "inputSchema": {
    "type": "object",
    "properties": {
      "query": {
        "type": "string",
        "description": "搜索关键词",
        "minLength": 1,
        "maxLength": 200
      },
      "count": {
        "type": "number",
        "description": "返回结果数量",
        "minimum": 1,
        "maximum": 10,
        "default": 5
      }
    },
    "required": ["query"]
  }
}

验证规则

规则	说明	示例
type	数据类型	string, number, boolean, object, array
required	必填字段	["query", "count"]
minimum/maximum	数值范围	minimum: 1, maximum: 100
minLength/maxLength	字符串长度	minLength: 1, maxLength: 200
enum	枚举值	["asc", "desc"]
pattern	正则匹配	"^[a-zA-Z]+$"

🔧 OpenClaw 实战应用

定义带验证的工具

// SKILL.md 中定义工具 Schema
---
name: my-tool
tools:
  - name: create_post
    description: "创建博客文章"
    input:
      type: object
      properties:
        title:
          type: string
          minLength: 1
          maxLength: 100
          description: "文章标题"
        content:
          type: string
          minLength: 100
          description: "文章内容"
        tags:
          type: array
          items:
            type: string
          minItems: 1
          maxItems: 10
          description: "文章标签"
      required: [title, content]
---

验证错误处理

// Schema 验证失败示例
工具调用: web_search({ query: "", count: 100 })

验证结果:
{
  "valid": false,
  "errors": [
    {
      "field": "query",
      "message": "String is too short (0 chars), minimum 1"
    },
    {
      "field": "count",
      "message": "Number is too large (100), maximum 10"
    }
  ]
}

🔗 相关概念