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crewAI/src/crewai/lite_agent.py
Vidit Ostwal e7a5747c6b
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Comparing BaseLLM class instead of LLM (#3120)
* Compaing BaseLLM class instead of LLM

* Fixed test cases

* Fixed Linting Issues

* removed last line

---------

Co-authored-by: Lucas Gomide <lucaslg200@gmail.com>
2025-07-11 20:50:36 -04:00

624 lines
22 KiB
Python

import asyncio
import inspect
import uuid
from typing import (
Any,
Callable,
Dict,
List,
Optional,
Tuple,
Type,
Union,
cast,
get_args,
get_origin,
)
try:
from typing import Self
except ImportError:
from typing_extensions import Self
from pydantic import (
UUID4,
BaseModel,
Field,
InstanceOf,
PrivateAttr,
model_validator,
field_validator
)
from crewai.agents.agent_builder.base_agent import BaseAgent
from crewai.agents.agent_builder.utilities.base_token_process import TokenProcess
from crewai.agents.cache import CacheHandler
from crewai.agents.parser import (
AgentAction,
AgentFinish,
OutputParserException,
)
from crewai.flow.flow_trackable import FlowTrackable
from crewai.llm import LLM, BaseLLM
from crewai.tools.base_tool import BaseTool
from crewai.tools.structured_tool import CrewStructuredTool
from crewai.utilities import I18N
from crewai.utilities.guardrail import process_guardrail
from crewai.utilities.agent_utils import (
enforce_rpm_limit,
format_message_for_llm,
get_llm_response,
get_tool_names,
handle_agent_action_core,
handle_context_length,
handle_max_iterations_exceeded,
handle_output_parser_exception,
handle_unknown_error,
has_reached_max_iterations,
is_context_length_exceeded,
parse_tools,
process_llm_response,
render_text_description_and_args,
)
from crewai.utilities.converter import generate_model_description
from crewai.utilities.events.agent_events import (
AgentLogsExecutionEvent,
LiteAgentExecutionCompletedEvent,
LiteAgentExecutionErrorEvent,
LiteAgentExecutionStartedEvent,
)
from crewai.utilities.events.crewai_event_bus import crewai_event_bus
from crewai.utilities.events.llm_events import (
LLMCallCompletedEvent,
LLMCallFailedEvent,
LLMCallStartedEvent,
LLMCallType,
)
from crewai.utilities.llm_utils import create_llm
from crewai.utilities.printer import Printer
from crewai.utilities.token_counter_callback import TokenCalcHandler
from crewai.utilities.tool_utils import execute_tool_and_check_finality
class LiteAgentOutput(BaseModel):
"""Class that represents the result of a LiteAgent execution."""
model_config = {"arbitrary_types_allowed": True}
raw: str = Field(description="Raw output of the agent", default="")
pydantic: Optional[BaseModel] = Field(
description="Pydantic output of the agent", default=None
)
agent_role: str = Field(description="Role of the agent that produced this output")
usage_metrics: Optional[Dict[str, Any]] = Field(
description="Token usage metrics for this execution", default=None
)
def to_dict(self) -> Dict[str, Any]:
"""Convert pydantic_output to a dictionary."""
if self.pydantic:
return self.pydantic.model_dump()
return {}
def __str__(self) -> str:
"""String representation of the output."""
if self.pydantic:
return str(self.pydantic)
return self.raw
class LiteAgent(FlowTrackable, BaseModel):
"""
A lightweight agent that can process messages and use tools.
This agent is simpler than the full Agent class, focusing on direct execution
rather than task delegation. It's designed to be used for simple interactions
where a full crew is not needed.
Attributes:
role: The role of the agent.
goal: The objective of the agent.
backstory: The backstory of the agent.
llm: The language model that will run the agent.
tools: Tools at the agent's disposal.
verbose: Whether the agent execution should be in verbose mode.
max_iterations: Maximum number of iterations for tool usage.
max_execution_time: Maximum execution time in seconds.
response_format: Optional Pydantic model for structured output.
"""
model_config = {"arbitrary_types_allowed": True}
# Core Agent Properties
id: UUID4 = Field(default_factory=uuid.uuid4, frozen=True)
role: str = Field(description="Role of the agent")
goal: str = Field(description="Goal of the agent")
backstory: str = Field(description="Backstory of the agent")
llm: Optional[Union[str, InstanceOf[BaseLLM], Any]] = Field(
default=None, description="Language model that will run the agent"
)
tools: List[BaseTool] = Field(
default_factory=list, description="Tools at agent's disposal"
)
# Execution Control Properties
max_iterations: int = Field(
default=15, description="Maximum number of iterations for tool usage"
)
max_execution_time: Optional[int] = Field(
default=None, description="Maximum execution time in seconds"
)
respect_context_window: bool = Field(
default=True,
description="Whether to respect the context window of the LLM",
)
use_stop_words: bool = Field(
default=True,
description="Whether to use stop words to prevent the LLM from using tools",
)
request_within_rpm_limit: Optional[Callable[[], bool]] = Field(
default=None,
description="Callback to check if the request is within the RPM limit",
)
i18n: I18N = Field(default=I18N(), description="Internationalization settings.")
# Output and Formatting Properties
response_format: Optional[Type[BaseModel]] = Field(
default=None, description="Pydantic model for structured output"
)
verbose: bool = Field(
default=False, description="Whether to print execution details"
)
callbacks: List[Callable] = Field(
default=[], description="Callbacks to be used for the agent"
)
# Guardrail Properties
guardrail: Optional[Union[Callable[[LiteAgentOutput], Tuple[bool, Any]], str]] = (
Field(
default=None,
description="Function or string description of a guardrail to validate agent output",
)
)
guardrail_max_retries: int = Field(
default=3, description="Maximum number of retries when guardrail fails"
)
# State and Results
tools_results: List[Dict[str, Any]] = Field(
default=[], description="Results of the tools used by the agent."
)
# Reference of Agent
original_agent: Optional[BaseAgent] = Field(
default=None, description="Reference to the agent that created this LiteAgent"
)
# Private Attributes
_parsed_tools: List[CrewStructuredTool] = PrivateAttr(default_factory=list)
_token_process: TokenProcess = PrivateAttr(default_factory=TokenProcess)
_cache_handler: CacheHandler = PrivateAttr(default_factory=CacheHandler)
_key: str = PrivateAttr(default_factory=lambda: str(uuid.uuid4()))
_messages: List[Dict[str, str]] = PrivateAttr(default_factory=list)
_iterations: int = PrivateAttr(default=0)
_printer: Printer = PrivateAttr(default_factory=Printer)
_guardrail: Optional[Callable] = PrivateAttr(default=None)
_guardrail_retry_count: int = PrivateAttr(default=0)
@model_validator(mode="after")
def setup_llm(self):
"""Set up the LLM and other components after initialization."""
self.llm = create_llm(self.llm)
if not isinstance(self.llm, BaseLLM):
raise ValueError(f"Expected LLM instance of type BaseLLM, got {type(self.llm).__name__}")
# Initialize callbacks
token_callback = TokenCalcHandler(token_cost_process=self._token_process)
self._callbacks = [token_callback]
return self
@model_validator(mode="after")
def parse_tools(self):
"""Parse the tools and convert them to CrewStructuredTool instances."""
self._parsed_tools = parse_tools(self.tools)
return self
@model_validator(mode="after")
def ensure_guardrail_is_callable(self) -> Self:
if callable(self.guardrail):
self._guardrail = self.guardrail
elif isinstance(self.guardrail, str):
from crewai.tasks.llm_guardrail import LLMGuardrail
if not isinstance(self.llm, BaseLLM):
raise TypeError(f"Guardrail requires LLM instance of type BaseLLM, got {type(self.llm).__name__}")
self._guardrail = LLMGuardrail(description=self.guardrail, llm=self.llm)
return self
@field_validator("guardrail", mode="before")
@classmethod
def validate_guardrail_function(
cls, v: Optional[Union[Callable, str]]
) -> Optional[Union[Callable, str]]:
"""Validate that the guardrail function has the correct signature.
If v is a callable, validate that it has the correct signature.
If v is a string, return it as is.
Args:
v: The guardrail function to validate or a string describing the guardrail task
Returns:
The validated guardrail function or a string describing the guardrail task
"""
if v is None or isinstance(v, str):
return v
# Check function signature
sig = inspect.signature(v)
if len(sig.parameters) != 1:
raise ValueError(
f"Guardrail function must accept exactly 1 parameter (LiteAgentOutput), "
f"but it accepts {len(sig.parameters)}"
)
# Check return annotation if present
if sig.return_annotation is not sig.empty:
if sig.return_annotation == Tuple[bool, Any]:
return v
origin = get_origin(sig.return_annotation)
args = get_args(sig.return_annotation)
if origin is not tuple or len(args) != 2 or args[0] is not bool:
raise ValueError(
"If return type is annotated, it must be Tuple[bool, Any]"
)
return v
@property
def key(self) -> str:
"""Get the unique key for this agent instance."""
return self._key
@property
def _original_role(self) -> str:
"""Return the original role for compatibility with tool interfaces."""
return self.role
def kickoff(self, messages: Union[str, List[Dict[str, str]]]) -> LiteAgentOutput:
"""
Execute the agent with the given messages.
Args:
messages: Either a string query or a list of message dictionaries.
If a string is provided, it will be converted to a user message.
If a list is provided, each dict should have 'role' and 'content' keys.
Returns:
LiteAgentOutput: The result of the agent execution.
"""
# Create agent info for event emission
agent_info = {
"role": self.role,
"goal": self.goal,
"backstory": self.backstory,
"tools": self._parsed_tools,
"verbose": self.verbose,
}
try:
# Reset state for this run
self._iterations = 0
self.tools_results = []
# Format messages for the LLM
self._messages = self._format_messages(messages)
return self._execute_core(agent_info=agent_info)
except Exception as e:
self._printer.print(
content="Agent failed to reach a final answer. This is likely a bug - please report it.",
color="red",
)
handle_unknown_error(self._printer, e)
# Emit error event
crewai_event_bus.emit(
self,
event=LiteAgentExecutionErrorEvent(
agent_info=agent_info,
error=str(e),
),
)
raise e
def _execute_core(self, agent_info: Dict[str, Any]) -> LiteAgentOutput:
# Emit event for agent execution start
crewai_event_bus.emit(
self,
event=LiteAgentExecutionStartedEvent(
agent_info=agent_info,
tools=self._parsed_tools,
messages=self._messages,
),
)
# Execute the agent using invoke loop
agent_finish = self._invoke_loop()
formatted_result: Optional[BaseModel] = None
if self.response_format:
try:
# Cast to BaseModel to ensure type safety
result = self.response_format.model_validate_json(agent_finish.output)
if isinstance(result, BaseModel):
formatted_result = result
except Exception as e:
self._printer.print(
content=f"Failed to parse output into response format: {str(e)}",
color="yellow",
)
# Calculate token usage metrics
usage_metrics = self._token_process.get_summary()
# Create output
output = LiteAgentOutput(
raw=agent_finish.output,
pydantic=formatted_result,
agent_role=self.role,
usage_metrics=usage_metrics.model_dump() if usage_metrics else None,
)
# Process guardrail if set
if self._guardrail is not None:
guardrail_result = process_guardrail(
output=output,
guardrail=self._guardrail,
retry_count=self._guardrail_retry_count,
)
if not guardrail_result.success:
if self._guardrail_retry_count >= self.guardrail_max_retries:
raise Exception(
f"Agent's guardrail failed validation after {self.guardrail_max_retries} retries. "
f"Last error: {guardrail_result.error}"
)
self._guardrail_retry_count += 1
if self.verbose:
self._printer.print(
f"Guardrail failed. Retrying ({self._guardrail_retry_count}/{self.guardrail_max_retries})..."
f"\n{guardrail_result.error}"
)
self._messages.append(
{
"role": "user",
"content": guardrail_result.error
or "Guardrail validation failed",
}
)
return self._execute_core(agent_info=agent_info)
# Apply guardrail result if available
if guardrail_result.result is not None:
if isinstance(guardrail_result.result, str):
output.raw = guardrail_result.result
elif isinstance(guardrail_result.result, BaseModel):
output.pydantic = guardrail_result.result
usage_metrics = self._token_process.get_summary()
output.usage_metrics = usage_metrics.model_dump() if usage_metrics else None
# Emit completion event
crewai_event_bus.emit(
self,
event=LiteAgentExecutionCompletedEvent(
agent_info=agent_info,
output=agent_finish.output,
),
)
return output
async def kickoff_async(
self, messages: Union[str, List[Dict[str, str]]]
) -> LiteAgentOutput:
"""
Execute the agent asynchronously with the given messages.
Args:
messages: Either a string query or a list of message dictionaries.
If a string is provided, it will be converted to a user message.
If a list is provided, each dict should have 'role' and 'content' keys.
Returns:
LiteAgentOutput: The result of the agent execution.
"""
return await asyncio.to_thread(self.kickoff, messages)
def _get_default_system_prompt(self) -> str:
"""Get the default system prompt for the agent."""
base_prompt = ""
if self._parsed_tools:
# Use the prompt template for agents with tools
base_prompt = self.i18n.slice("lite_agent_system_prompt_with_tools").format(
role=self.role,
backstory=self.backstory,
goal=self.goal,
tools=render_text_description_and_args(self._parsed_tools),
tool_names=get_tool_names(self._parsed_tools),
)
else:
# Use the prompt template for agents without tools
base_prompt = self.i18n.slice(
"lite_agent_system_prompt_without_tools"
).format(
role=self.role,
backstory=self.backstory,
goal=self.goal,
)
# Add response format instructions if specified
if self.response_format:
schema = generate_model_description(self.response_format)
base_prompt += self.i18n.slice("lite_agent_response_format").format(
response_format=schema
)
return base_prompt
def _format_messages(
self, messages: Union[str, List[Dict[str, str]]]
) -> List[Dict[str, str]]:
"""Format messages for the LLM."""
if isinstance(messages, str):
messages = [{"role": "user", "content": messages}]
system_prompt = self._get_default_system_prompt()
# Add system message at the beginning
formatted_messages = [{"role": "system", "content": system_prompt}]
# Add the rest of the messages
formatted_messages.extend(messages)
return formatted_messages
def _invoke_loop(self) -> AgentFinish:
"""
Run the agent's thought process until it reaches a conclusion or max iterations.
Returns:
AgentFinish: The final result of the agent execution.
"""
# Execute the agent loop
formatted_answer = None
while not isinstance(formatted_answer, AgentFinish):
try:
if has_reached_max_iterations(self._iterations, self.max_iterations):
formatted_answer = handle_max_iterations_exceeded(
formatted_answer,
printer=self._printer,
i18n=self.i18n,
messages=self._messages,
llm=cast(LLM, self.llm),
callbacks=self._callbacks,
)
enforce_rpm_limit(self.request_within_rpm_limit)
# Emit LLM call started event
crewai_event_bus.emit(
self,
event=LLMCallStartedEvent(
messages=self._messages,
tools=None,
callbacks=self._callbacks,
from_agent=self,
),
)
try:
answer = get_llm_response(
llm=cast(LLM, self.llm),
messages=self._messages,
callbacks=self._callbacks,
printer=self._printer,
from_agent=self,
)
# Emit LLM call completed event
crewai_event_bus.emit(
self,
event=LLMCallCompletedEvent(
messages=self._messages,
response=answer,
call_type=LLMCallType.LLM_CALL,
from_agent=self,
),
)
except Exception as e:
# Emit LLM call failed event
crewai_event_bus.emit(
self,
event=LLMCallFailedEvent(error=str(e), from_agent=self),
)
raise e
formatted_answer = process_llm_response(answer, self.use_stop_words)
if isinstance(formatted_answer, AgentAction):
try:
tool_result = execute_tool_and_check_finality(
agent_action=formatted_answer,
tools=self._parsed_tools,
i18n=self.i18n,
agent_key=self.key,
agent_role=self.role,
agent=self.original_agent,
)
except Exception as e:
raise e
formatted_answer = handle_agent_action_core(
formatted_answer=formatted_answer,
tool_result=tool_result,
show_logs=self._show_logs,
)
self._append_message(formatted_answer.text, role="assistant")
except OutputParserException as e:
formatted_answer = handle_output_parser_exception(
e=e,
messages=self._messages,
iterations=self._iterations,
log_error_after=3,
printer=self._printer,
)
except Exception as e:
if e.__class__.__module__.startswith("litellm"):
# Do not retry on litellm errors
raise e
if is_context_length_exceeded(e):
handle_context_length(
respect_context_window=self.respect_context_window,
printer=self._printer,
messages=self._messages,
llm=cast(LLM, self.llm),
callbacks=self._callbacks,
i18n=self.i18n,
)
continue
else:
handle_unknown_error(self._printer, e)
raise e
finally:
self._iterations += 1
assert isinstance(formatted_answer, AgentFinish)
self._show_logs(formatted_answer)
return formatted_answer
def _show_logs(self, formatted_answer: Union[AgentAction, AgentFinish]):
"""Show logs for the agent's execution."""
crewai_event_bus.emit(
self,
AgentLogsExecutionEvent(
agent_role=self.role,
formatted_answer=formatted_answer,
verbose=self.verbose,
),
)
def _append_message(self, text: str, role: str = "assistant") -> None:
"""Append a message to the message list with the given role."""
self._messages.append(format_message_for_llm(text, role=role))