Use safe expression parser in calculator tool example (#6211)

* Replace eval with safe expression parser in calculator tool example

Update the calculator tool example in the CLI template to use
ast.parse instead of eval for expression evaluation.

Co-authored-by: Vinicius Brasil <vini@hey.com>

* Replace calculator example with practical file reader tool

* Use word count example - safe, no file/eval risk

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Co-authored-by: Vinicius Brasil <vini@hey.com>

lib/cli/src/crewai_cli/templates/AGENTS.md

@@ -767,10 +767,11 @@ class CustomSearchTool(BaseTool):
 ```python
 from crewai.tools import tool
 
-@tool("Calculator")
-def calculator(expression: str) -> str:
-    """Evaluates a mathematical expression and returns the result."""
-    return str(eval(expression))
+@tool("WordCount")
+def word_count(text: str) -> str:
+    """Counts the number of words in the given text."""
+    count = len(text.split())
+    return f"Word count: {count}"
 ```
 
 ### Built-in Tools (install with `uv add crewai-tools`)