# studio-arity

> A function or expression is called with the wrong number of values.

| | |
| --- | --- |
| Kind | Studio problem |
| Reported by | Studio validation: the Problems panel, Play, Publish and the MCP `validate` tool |
| Code in the Studio | `arity` |

Built-in functions and your own expressions take a fixed number of parameters. `max(a, b)` takes two; an expression with one parameter takes one.

## Fix

- Pass exactly the values the function takes. The field's hint lists them.

## See also

- [Problems and validation](/studio/playtesting)