agent2: Clean up tool descriptions (#36619)

schemars was passing along the newlines from the doc comments. This
should make these closer to the markdown file versions we had in the old
agent.

Release Notes:

- N/A

crates/agent2/src/tools/web_search_tool.rs

@@ -14,7 +14,7 @@ use ui::prelude::*;
 use web_search::WebSearchRegistry;
 
 /// Search the web for information using your query.
-/// Use this when you need real-time information, facts, or data that might not be in your training. \
+/// Use this when you need real-time information, facts, or data that might not be in your training.
 /// Results will include snippets and links from relevant web pages.
 #[derive(Debug, Serialize, Deserialize, JsonSchema)]
 pub struct WebSearchToolInput {