Your OpenAPI schema, turned into code you’d have written yourself

paths:
  /pets/{id}:
    get:
      operationId: getPet
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'
components:
  schemas:
    Pet:
      type: object
      required: [id, name]
      properties:
        id: { type: integer }
        name: { type: string }
        tag: { type: string }

export const pet = z.object({
  id: z.number().int(),
  name: z.string(),
  tag: z.string().optional()
})

export type Pet = z.infer<typeof pet>

export const useGetPet = ({ id }: GetPetArgs) =>
  useQuery({
    queryKey: ['pets', id],
    queryFn: async () => {
      const res = await fetch(`${baseUrl}/pets/${id}`)
      return pet.parse(await res.json())
    }
  })