---

This section details on the original issue you should resolve

<issue_title>Default RequestSchema for form mode breaking change</issue_title>
<issue_description>Prior to adding support for url elicitations, RequestedSchema defaulted to an empty object schema. Now if you don't supply a schema, elicitation requests throw. Was this an intentional breaking change?
cc: @halter73 </issue_description>

<agent_instructions>Please just add a test validating the ArgumentException discussed.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@halter73 I assume you saw [the ArgumentException](https://github.com/modelcontextprotocol/csharp-sdk/blob/774411b22c2797055fd8d2dde7c9dfaf1cc2bd52/src/ModelContextProtocol.Core/Server/McpServer.Methods.cs#L495) complaining "Form mode elicitation requests require a requested schema."? I did intentionally add that in https://github.com//pull/1021. I figured that it didn't make sense to do a form-mode elicitation without any parameters, so it's better to raise an error as quickly as possible.

It appears I didn't add a test verifying we throw this ArgumentException though. I can add that. Or do you think we should revert the behavior?</comment_new>
<comment_new>@stephentoub

I figured that it didn't make sense to do a form-mode elicitation without any parameters

I agree it's an oddity and likely indicative of a bug. As long as it was an intentional change, I think it's ok.

And we can't make the schema required because it's not necessary for url mode?</comment_new>
<comment_new>@halter73

And we can't make the schema required because it's not necessary for url mode?

Exactly.</comment_new>