feat: Add LLM call events for improved observability (#2214)

* feat: Add LLM call events for improved observability

- Introduce new LLM call events: LLMCallStartedEvent, LLMCallCompletedEvent, and LLMCallFailedEvent
- Emit events for LLM calls and tool calls to provide better tracking and debugging
- Add event handling in the LLM class to track call lifecycle
- Update event bus to support new LLM-related events
- Add test cases to validate LLM event emissions

* feat: Add event handling for LLM call lifecycle events

- Implement event listeners for LLM call events in EventListener
- Add logging for LLM call start, completion, and failure events
- Import and register new LLM-specific event types

* less log

* refactor: Update LLM event response type to support Any

* refactor: Simplify LLM call completed event emission

Remove unnecessary LLMCallType conversion when emitting LLMCallCompletedEvent

* refactor: Update LLM event docstrings for clarity

Improve docstrings for LLM call events to more accurately describe their purpose and lifecycle

* feat: Add LLMCallFailedEvent emission for tool execution errors

Enhance error handling by emitting a specific event when tool execution fails during LLM calls

src/crewai/utilities/events/__init__.py

@@ -34,6 +34,7 @@ from .tool_usage_events import (
     ToolUsageEvent,
     ToolValidateInputErrorEvent,
 )
+from .llm_events import LLMCallCompletedEvent, LLMCallFailedEvent, LLMCallStartedEvent
 
 # events
 from .event_listener import EventListener

src/crewai/utilities/events/event_listener.py

@@ -4,6 +4,11 @@ from crewai.telemetry.telemetry import Telemetry
 from crewai.utilities import Logger
 from crewai.utilities.constants import EMITTER_COLOR
 from crewai.utilities.events.base_event_listener import BaseEventListener
+from crewai.utilities.events.llm_events import (
+    LLMCallCompletedEvent,
+    LLMCallFailedEvent,
+    LLMCallStartedEvent,
+)
 
 from .agent_events import AgentExecutionCompletedEvent, AgentExecutionStartedEvent
 from .crew_events import (
@@ -253,5 +258,28 @@ class EventListener(BaseEventListener):
                 #
             )
 
+        # ----------- LLM EVENTS -----------
+
+        @crewai_event_bus.on(LLMCallStartedEvent)
+        def on_llm_call_started(source, event: LLMCallStartedEvent):
+            self.logger.log(
+                f"🤖 LLM Call Started",
+                event.timestamp,
+            )
+
+        @crewai_event_bus.on(LLMCallCompletedEvent)
+        def on_llm_call_completed(source, event: LLMCallCompletedEvent):
+            self.logger.log(
+                f"✅ LLM Call Completed",
+                event.timestamp,
+            )
+
+        @crewai_event_bus.on(LLMCallFailedEvent)
+        def on_llm_call_failed(source, event: LLMCallFailedEvent):
+            self.logger.log(
+                f"❌ LLM Call Failed: '{event.error}'",
+                event.timestamp,
+            )
+
 
 event_listener = EventListener()

src/crewai/utilities/events/llm_events.py

@@ -0,0 +1,36 @@
+from enum import Enum
+from typing import Any, Dict, List, Optional, Union
+
+from crewai.utilities.events.base_events import CrewEvent
+
+
+class LLMCallType(Enum):
+    """Type of LLM call being made"""
+
+    TOOL_CALL = "tool_call"
+    LLM_CALL = "llm_call"
+
+
+class LLMCallStartedEvent(CrewEvent):
+    """Event emitted when a LLM call starts"""
+
+    type: str = "llm_call_started"
+    messages: Union[str, List[Dict[str, str]]]
+    tools: Optional[List[dict]] = None
+    callbacks: Optional[List[Any]] = None
+    available_functions: Optional[Dict[str, Any]] = None
+
+
+class LLMCallCompletedEvent(CrewEvent):
+    """Event emitted when a LLM call completes"""
+
+    type: str = "llm_call_completed"
+    response: Any
+    call_type: LLMCallType
+
+
+class LLMCallFailedEvent(CrewEvent):
+    """Event emitted when a LLM call fails"""
+
+    error: str
+    type: str = "llm_call_failed"

src/crewai/utilities/events/task_events.py

@@ -1,4 +1,4 @@
-from typing import Any, Optional
+from typing import Optional
 
 from crewai.tasks.task_output import TaskOutput
 from crewai.utilities.events.base_events import CrewEvent