Collect every valid x-mcp-header annotation in a tool inputSchema,
recursing into nested object properties and arrayitems schemas — the
draft permits the annotation "at any nesting depth within the inputSchema,
not only top-level properties". Annotations on non-primitive
(number/object/array) properties, or with an invalid value, are skipped
here; use validateInputSchemaHeaders to reject such schemas up front.
Collect every valid x-mcp-header annotation in a tool inputSchema, recursing into nested object properties and array items schemas — the draft permits the annotation "at any nesting depth within the inputSchema, not only top-level properties". Annotations on non-primitive (number/object/array) properties, or with an invalid value, are skipped here; use validateInputSchemaHeaders to reject such schemas up front.