Validate Claude tool definitions
Claude’s tool use relies on a precise tool schema, and a malformed input_schema
or a thin description leads to rejected requests or poor tool selection. Paste
your tool definition here and get an instant checklist against Anthropic’s
spec — name format, description quality, input_schema structure, property
types, and nesting depth — before you add it to your tools array.
How it works
The validator parses your JSON and checks the shape Anthropic expects: a flat
object with name, description, and input_schema. Unlike OpenAI’s nested
function.parameters, Anthropic puts the JSON Schema directly under
input_schema, which must be { "type": "object", "properties": { … } }. The
tool verifies the name matches the allowed pattern, the description is present
and substantive, every property declares a type, and the schema isn’t nested too
deeply for Claude to fill reliably.
Tips
- Write rich descriptions. Claude leans on the tool description more than most models; explain when to use the tool and what each field means.
- Use
requiredexplicitly so Claude knows which inputs it must provide. - Prefer enums and flat structures over free-form strings and deep nesting — they produce far more reliable tool calls.