Adds clarifying examples and information about the `include_pattern`
parameter for the grep tool, analogous to the `path` parameter of the
read and list tools and others.
The lack of clarity led to unexpected agent behavior described in
#41189. This change is confirmed to improve the precision of Claude
Sonnet 4.5 when searching for code in an empty conversation (without it,
it leaves out the root directory in the query).
Closes#41189.
```
Release Notes:
- Clarify grep tool description to improve agent precision when using it with the `include_pattern` parameter
```
d4c0b87fb2