What an anagram is
An anagram uses every letter of the original exactly once — no more, no fewer. That strict rule is what separates anagramming from general unscrambling. If your input is "listen", the anagram solver will return "silent" and "tinsel" but not "list" or "line", because those leave letters unused.
Anagrams can be single words ("triangle" → "integral") or multi-word phrases ("astronomer" → "moon starer"). Most solvers focus on single-word anagrams because multi-word anagrams explode in number and are judged more for wit than for completeness.