How to document swagger request parameter using json object input

Question

How to determine the value of a JSON object for a request parameter that is in: query(not in: body)?

Example below:

paths:
  /schedules:
    get:
      summary: Gets the list of schedules
      description: |
        The schedules endpoint returns information about the configured schedules.
      parameters:
        - name: filter
          in: query
          description: >
          Returns whether alert runs on matching schedule.


          Example request:


              {
                "type": "a",
                "start" : "b",
                "stop" : "c"
              }
          required: true
          type: string

Since it is not in: body, I can not use schema.