Tool Definitions
The tool definition is how Claude knows what your tool does. Build one interactively and watch the JSON schema generate in real-time.
Build a Tool Definition
JSON Schema is a standard way to describe the shape of data -- what fields exist, what types they are (string, number, etc.), and which ones are required. Claude reads these schemas to understand what inputs your tool needs and how to format them correctly.
Why tool definitions matter: Without a clear definition, Claude has no way to know your tool exists or how to call it. The definition is your tool's instruction manual -- the better you describe it, the more accurately Claude will use it. Fill in the fields below and watch the schema update live on the right.
Test Your Tool
Enter example values for each parameter to see what a tool call would look like:
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