workflow-syntax reference: description, default and options keys for on.workflow_dispatch.inputs.<input_id> are undocumented #46354

Where the gap is

content/actions/reference/workflows-and-actions/workflow-syntax.md documents required and type for on.workflow_dispatch.inputs.<input_id>, but three sibling keys that the workflow syntax accepts are missing from the reference:

• description: a string describing the input, shown in the workflow dispatch UI
• default: the value used when the workflow is triggered manually without a value supplied
• options: the list of strings shown in the dropdown for an input whose type is choice

Why it matters

The workflow syntax reference is the page people land on when validating a workflow_dispatch block. The three undocumented keys behave differently from what a reader might guess (for example options is only valid for choice inputs, and default for a choice input must be one of the listed options), so having them absent from the reference leads to trial-and-error. The dedicated workflow_dispatch event page (actions/using-workflows.../events-that-trigger-workflows / workflow-dispatch event doc) does cover these keys, so the gap is specifically the syntax reference page.

Suggested fix

Add the three subsections between the existing required and type subsections, in the same style:

• on.workflow_dispatch.inputs.<input_id>.description: a string description of the input parameter.
• on.workflow_dispatch.inputs.<input_id>.default: the default value used when the workflow is triggered manually without a value being supplied for the input.
• on.workflow_dispatch.inputs.<input_id>.options: a list of strings containing the options shown in the dropdown list when the workflow is triggered manually; only usable when the input's type is choice.

Happy to open the corresponding PR once this issue is triaged.