Search the web with `query`. Results come back as short highlights, each with an expand ID; call the tool again with `expand` set to that ID to retrieve the full cached text of that result. `query` and `expand` are mutually exclusive — pass exactly one per call. Expand IDs are session-scoped: they work only if a search ran earlier in this same session. Pass `pictures` only when you need to see what something looks like: the answer then also lists pictures of the results' subjects, each with its address and hosting page, or says that none were usable.