Tool Use & Function Calling

How do you define nested objects in Claude's tool schema?

Last verified: July 2026 · 2 min read
QUICK ANSWER

Define nested structures by nesting object properties inside properties in your tool definition, matching the JSON Schema Draft 4 specification.

Nested Schema Example

{
  "name": "update_user_profile",
  "description": "Updates profile details.",
  "input_schema": {
    "type": "object",
    "properties": {
      "user_id": { "type": "string" },
      "profile": {
        "type": "object",
        "properties": {
          "name": { "type": "string" },
          "email": { "type": "string" }
        },
        "required": ["name"]
      }
    },
    "required": ["user_id", "profile"]
  }
}
Verified against: Anthropic API Tool Use v1

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