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.

crewai/crew.py

@@ -1,10 +1,18 @@
 import json
 from typing import Any, Dict, List, Optional, Union
 
-from pydantic import BaseModel, Field, Json, field_validator, model_validator
+from pydantic import (
+    BaseModel,
+    Field,
+    InstanceOf,
+    Json,
+    field_validator,
+    model_validator,
+)
 from pydantic_core import PydanticCustomError
 
 from .agent import Agent
+from .agents import CacheHandler
 from .process import Process
 from .task import Task
 from .tools.agent_tools import AgentTools
@@ -13,6 +21,9 @@ from .tools.agent_tools import AgentTools
 class Crew(BaseModel):
     """Class that represents a group of agents, how they should work together and their tasks."""
 
+    class Config:
+        arbitrary_types_allowed = True
+
     tasks: List[Task] = Field(description="List of tasks", default_factory=list)
     agents: List[Agent] = Field(
         description="List of agents in this crew.", default_factory=list
@@ -26,6 +37,9 @@ class Crew(BaseModel):
     config: Optional[Union[Json, Dict[str, Any]]] = Field(
         description="Configuration of the crew.", default=None
     )
+    cache_handler: Optional[InstanceOf[CacheHandler]] = Field(
+        default=CacheHandler(), description="An instance of the CacheHandler class."
+    )
 
     @classmethod
     @field_validator("config", mode="before")
@@ -58,6 +72,10 @@ class Crew(BaseModel):
                 tasks.append(Task(**task, agent=task_agent))
 
             self.tasks = tasks
+
+        if self.agents:
+            for agent in self.agents:
+                agent.set_cache_handler(self.cache_handler)
         return self
 
     def kickoff(self) -> str:
@@ -66,6 +84,9 @@ class Crew(BaseModel):
         Returns:
             Output of the crew for each task.
         """
+        for agent in self.agents:
+            agent.cache_handler = self.cache_handler
+
         if self.process == Process.sequential:
             return self.__sequential_loop()