Improve prompts for tools (#11669)

Improves the descriptions for some of the tools. I wish we had metrics
to back up changes in how the model responds to tool schema changes so
anecdotally I'm just going to say this _seems_ improved.

Release Notes:

- N/A

Cargo.lock

@@ -383,6 +383,7 @@ dependencies = [
  "editor",
  "env_logger",
  "feature_flags",
+ "file_icons",
  "fs",
  "futures 0.3.28",
  "fuzzy",
@@ -406,6 +407,7 @@ dependencies = [
  "story",
  "theme",
  "ui",
+ "unindent",
  "util",
  "workspace",
 ]