agent: Add more Rust code examples, update TODO check (#28737)

Release Notes:

- N/A

script/check-todos

@@ -4,7 +4,10 @@ set -euo pipefail
 
 # Brackets are used around characters so these don't show up in normal search.
 pattern='tod[o]!|FIXM[E]'
-result=$(git grep --no-color --ignore-case --line-number --extended-regexp -e $pattern -- ':(exclude).github/workflows/ci.yml' || true)
+result=$(git grep --no-color --ignore-case --line-number --extended-regexp -e $pattern -- \
+  ':(exclude).github/workflows/ci.yml' \
+  ':(exclude)*criteria.md' \
+  ':(exclude)*prompt.md' || true)
 echo "${result}"
 if [[ -n "${result}" ]]; then
   exit 1