fix: handle tool descriptions with curly braces in agent interpolation

- Add _interpolate_only helper method to escape curly braces
- Update interpolate_inputs to use new helper
- Add test case for tool descriptions
- Fixes #2145

Co-Authored-By: Joe Moura <joao@crewai.com>

src/crewai/agents/agent_builder/base_agent.py

@@ -314,6 +314,15 @@ class BaseAgent(ABC, BaseModel):
 
         return copied_agent
 
+    def _interpolate_only(self, input_string: str, inputs: Dict[str, Any]) -> str:
+        """Interpolate placeholders (e.g., {key}) in a string while leaving JSON untouched."""
+        escaped_string = input_string.replace("{", "{{").replace("}", "}}")
+
+        for key in inputs.keys():
+            escaped_string = escaped_string.replace(f"{{{{{key}}}}}", f"{{{key}}}")
+
+        return escaped_string.format(**inputs)
+
     def interpolate_inputs(self, inputs: Dict[str, Any]) -> None:
         """Interpolate inputs into the agent description and backstory."""
         if self._original_role is None:
@@ -324,9 +333,9 @@ class BaseAgent(ABC, BaseModel):
             self._original_backstory = self.backstory
 
         if inputs:
-            self.role = self._original_role.format(**inputs)
-            self.goal = self._original_goal.format(**inputs)
-            self.backstory = self._original_backstory.format(**inputs)
+            self.role = self._interpolate_only(self._original_role, inputs)
+            self.goal = self._interpolate_only(self._original_goal, inputs)
+            self.backstory = self._interpolate_only(self._original_backstory, inputs)
 
     def set_cache_handler(self, cache_handler: CacheHandler) -> None:
         """Set the cache handler for the agent.

tests/agent_test.py

@@ -1357,6 +1357,32 @@ def test_handle_context_length_exceeds_limit_cli_no():
             mock_handle_context.assert_not_called()
 
 
+def test_interpolate_inputs_with_tool_description():
+    from crewai.tools import BaseTool
+    
+    class DummyTool(BaseTool):
+        name: str = "dummy_tool"
+        description: str = "Tool Arguments: {'arg': {'description': 'test arg', 'type': 'str'}}"
+        
+        def _run(self, arg: str) -> str:
+            """Run the tool."""
+            return f"Dummy result for: {arg}"
+    
+    tool = DummyTool()
+    agent = Agent(
+        role="{topic} specialist",
+        goal="Figure {goal} out",
+        backstory="I am the master of {role}\nTools: {tool_desc}",
+    )
+
+    agent.interpolate_inputs({
+        "topic": "AI",
+        "goal": "life",
+        "role": "all things",
+        "tool_desc": tool.description
+    })
+    assert "Tool Arguments: {'arg': {'description': 'test arg', 'type': 'str'}}" in agent.backstory
+
 def test_agent_with_all_llm_attributes():
     agent = Agent(
         role="test role",