# X_INPUT_INVALID

## Means

input failed the primitive's schema — an action's, and a query's too

## Typical cause

wrong shape from a client or an agent; over HTTP it is a **400**, never a 500; over MCP an `isError` tool result (`As of 22.10`)

## Fix

`x actions show <name> --json` (`x queries show <name> --json` for a read)

[Actions](/error-codes#actions)