Since arguments to CLI tools often are file systems paths, I think it could be useful to also have "file path" and "directory path" types to allow for more stongly-typed clients to be generated (rather than treating all paths as strings).

Also, CLIs often define a finite set of allowed values for a argument, so something like an user defined "enum type" could be useful.
maybe something along the lines of JSON Schema's Enumerated values

File paths in one CLI framework: https://ajalt.github.io/clikt/parameters/#file-paths

I would extend it event further and introduce "non existent file path" and "existing file path" as there are tools that expect the passed argument to exist (consumers) and not (often asking if the file should be overridden if it's present).

In the Clikt framework mentioned above, it is possible to express whether this path should be a directory, a file, or either; whether it should already exist, must not exist, or it doesn't matter; whether it should be readable, writable, or both, etc. It would be nice if the spec could encompass that as well.

I suggest we also support pattern property for strings, to restrict the syntax of a string with a regular expression, like OpenAPI and JSON Schema: https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-validation-01#section-6.3.3

I suggest we also support enum property for strings, to restrict the value to a fixed set, like OpenAPI and JSON Schema: https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-validation-01#section-6.1.2

I suggest the url format is named uri to avoid confusion, and to be consistent with OpenAPI and JSON Schema: https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-validation-01#name-resource-identifiers

I suggest we don't have a float type, since binary floating-point numbers have surprising semantics, and are most of the time not what you would want in this context. A proper decimal type would be better, but best to leave non-integer numbers out completely, you can always encode them as string anyway (especially if we support a regular expression pattern).

(At least, the minimum/maximum values should be exclusive (open range) for float, since close ranges and equality comparisons are not recommended.)

File or directory paths are super useful. I would also like to have other symbols typed like the - symbol for stdin which is common

Unfortunately, the JSON schema spec has no format for files. Given how crucial they are for this domain, I think an exception should be made for them, and also further semantics as mentioned in previous comments.

It should be possible to cover the syntactic restrictions of stringy types with formats and, where unavailable, pattern.

Neither is available for numeric types, although some can modelled using min and max.