Support Type Aliases

[RPGillespie6]

Is your feature request related to a problem? Please describe.
If I try to use an aliased type, such as:

type Time time.Time

The MCP tool starts failing with:

{"error":"MCP error 0: validating tool output: validating root: validating /properties/fields: validating /properties/fields/properties/customdate: type: 0001-01-01 has type \"string\", want \"object\""}

Running into this because go-jira uses its own time.Time alias

Describe the solution you'd like
Since time.Time is treated as a string in the schema, aliases of time.Time should also be treated as a string since they both serialize to the same output with json.Marshal