Adding tool caching a loop execution prevention. (#25)

* Adding tool caching a loop execution prevention.

This adds some guardrails, to both prevent the same tool to be used
consecutively and also caching tool's results across the entire crew
so it cuts down execution time and eventual LLM calls.

This plays a huge role for smaller opensource models that usually fall
into those behaviors patterns.

It also includes some smaller improvements around the tool prompt and
agent tools, all with the same intention of guiding models into
better conform with agent instructions.

tests/agent_test.py

@@ -4,6 +4,7 @@ import pytest
 from langchain.chat_models import ChatOpenAI as OpenAI
 
 from crewai.agent import Agent
+from crewai.agents import CacheHandler
 
 
 def test_agent_creation():
@@ -101,6 +102,77 @@ def test_agent_execution_with_tools():
     assert output == "12"
 
 
+@pytest.mark.vcr(filter_headers=["authorization"])
+def test_logging_tool_usage():
+    from langchain.tools import tool
+
+    @tool
+    def multiplier(numbers) -> float:
+        """Useful for when you need to multiply two numbers together.
+        The input to this tool should be a comma separated list of numbers of
+        length two, representing the two numbers you want to multiply together.
+        For example, `1,2` would be the input if you wanted to multiply 1 by 2."""
+        a, b = numbers.split(",")
+        return int(a) * int(b)
+
+    agent = Agent(
+        role="test role",
+        goal="test goal",
+        backstory="test backstory",
+        tools=[multiplier],
+        allow_delegation=False,
+        verbose=True,
+    )
+
+    assert agent.tools_handler.last_used_tool == {}
+    output = agent.execute_task("What is 3 times 5?")
+    tool_usage = {
+        "tool": "multiplier",
+        "input": "3,5",
+    }
+
+    assert output == "3 times 5 is 15."
+    assert agent.tools_handler.last_used_tool == tool_usage
+
+
+@pytest.mark.vcr(filter_headers=["authorization"])
+def test_cache_hitting():
+    from unittest.mock import patch
+
+    from langchain.tools import tool
+
+    @tool
+    def multiplier(numbers) -> float:
+        """Useful for when you need to multiply two numbers together.
+        The input to this tool should be a comma separated list of numbers of
+        length two, representing the two numbers you want to multiply together.
+        For example, `1,2` would be the input if you wanted to multiply 1 by 2."""
+        a, b = numbers.split(",")
+        return int(a) * int(b)
+
+    cache_handler = CacheHandler()
+
+    agent = Agent(
+        role="test role",
+        goal="test goal",
+        backstory="test backstory",
+        tools=[multiplier],
+        allow_delegation=False,
+        cache_handler=cache_handler,
+        verbose=True,
+    )
+
+    output = agent.execute_task("What is 2 times 6?")
+    output = agent.execute_task("What is 3 times 3?")
+    assert cache_handler._cache == {"multiplier-2,6": "12", "multiplier-3,3": "9"}
+
+    with patch.object(CacheHandler, "read") as read:
+        read.return_value = "0"
+        output = agent.execute_task("What is 2 times 6?")
+        assert output == "0"
+        read.assert_called_once_with("multiplier", "2,6")
+
+
 @pytest.mark.vcr(filter_headers=["authorization"])
 def test_agent_execution_with_specific_tools():
     from langchain.tools import tool
@@ -122,4 +194,4 @@ def test_agent_execution_with_specific_tools():
     )
 
     output = agent.execute_task(task="What is 3 times 4", tools=[multiplier])
-    assert output == "3 times 4 is 12."
+    assert output == "12"