Use Annotated[pydantic.AnyUrl, pydantic.UrlConstraints(host_required=False)] instead of AnyUrl

[dsp-ant]

Pydantic's AnyUrl requires a host to be specified. For file resources this means that a triple slash such as file:///foo.txt is required because there is no host. We should likely be using Annotated[pydantic.AnyUrl, pydantic.UrlConstraints(host_required=False)] or something along these lines.

[jspahrsummers]

Looks like this is affecting https://github.com/modelcontextprotocol/python-sdk/tree/main/examples/servers/simple-resource:

MCP error 0: 1 validation error for function-wrap[wrap_val()]
  Input should be a valid URL, empty host [type=url_parsing, input_value='file:///greeting.txt', input_type=str]
    For further information visit https://errors.pydantic.dev/2.10/v/url_parsing