Add tags in agent initialization (#6559)

Add better docstrings for agent executor as well

Inspo: https://github.com/hwchase17/langchainjs/pull/1722

![image](https://github.com/hwchase17/langchain/assets/130414180/d11662bc-0c0e-4166-9ff3-354d41a9144a)

langchain/agents/agent.py

@@ -621,14 +621,44 @@ class AgentExecutor(Chain):
     """Consists of an agent using tools."""
 
     agent: Union[BaseSingleActionAgent, BaseMultiActionAgent]
+    """The agent to run for creating a plan and determining actions
+    to take at each step of the execution loop."""
     tools: Sequence[BaseTool]
+    """The valid tools the agent can call."""
     return_intermediate_steps: bool = False
+    """Whether to return the agent's trajectory of intermediate steps
+    at the end in addition to the final output."""
     max_iterations: Optional[int] = 15
+    """The maximum number of steps to take before ending the execution
+    loop.
+    
+    Setting to 'None' could lead to an infinite loop."""
     max_execution_time: Optional[float] = None
+    """The maximum amount of wall clock time to spend in the execution
+    loop.
+    """
     early_stopping_method: str = "force"
+    """The method to use for early stopping if the agent never
+    returns `AgentFinish`. Either 'force' or 'generate'.
+
+    `"force"` returns a string saying that it stopped because it met a
+        time or iteration limit.
+    
+    `"generate"` calls the agent's LLM Chain one final time to generate
+        a final answer based on the previous steps.
+    """
     handle_parsing_errors: Union[
         bool, str, Callable[[OutputParserException], str]
     ] = False
+    """How to handle errors raised by the agent's output parser.
+    Defaults to `False`, which raises the error.
+s
+    If `true`, the error will be sent back to the LLM as an observation.
+    If a string, the string itself will be sent to the LLM as an observation.
+    If a callable function, the function will be called with the exception
+     as an argument, and the result of that function will be passed to the agent
+      as an observation.
+    """
 
     @classmethod
     def from_agent_and_tools(

langchain/agents/initialize.py

@@ -16,6 +16,8 @@ def initialize_agent(
     callback_manager: Optional[BaseCallbackManager] = None,
     agent_path: Optional[str] = None,
     agent_kwargs: Optional[dict] = None,
+    *,
+    tags: Optional[Sequence[str]] = None,
     **kwargs: Any,
 ) -> AgentExecutor:
     """Load an agent executor given tools and LLM.
@@ -29,11 +31,13 @@ def initialize_agent(
             not provided. Defaults to None.
         agent_path: Path to serialized agent to use.
         agent_kwargs: Additional key word arguments to pass to the underlying agent
+        tags: Tags to apply to the traced runs.
         **kwargs: Additional key word arguments passed to the agent executor
 
     Returns:
         An agent executor
     """
+    tags_ = list(tags) if tags else []
     if agent is None and agent_path is None:
         agent = AgentType.ZERO_SHOT_REACT_DESCRIPTION
     if agent is not None and agent_path is not None:
@@ -47,6 +51,7 @@ def initialize_agent(
                 f"Got unknown agent type: {agent}. "
                 f"Valid types are: {AGENT_TO_CLASS.keys()}."
             )
+        tags_.append(agent.value)
         agent_cls = AGENT_TO_CLASS[agent]
         agent_kwargs = agent_kwargs or {}
         agent_obj = agent_cls.from_llm_and_tools(
@@ -56,6 +61,11 @@ def initialize_agent(
         agent_obj = load_agent(
             agent_path, llm=llm, tools=tools, callback_manager=callback_manager
         )
+        try:
+            # TODO: Add tags from the serialized object directly.
+            tags_.append(agent_obj._agent_type)
+        except NotImplementedError:
+            pass
     else:
         raise ValueError(
             "Somehow both `agent` and `agent_path` are None, "
@@ -65,5 +75,6 @@ def initialize_agent(
         agent=agent_obj,
         tools=tools,
         callback_manager=callback_manager,
+        tags=tags_,
         **kwargs,
     )