chore: refine usage limit comments

- Updated docstrings in `RunContext`, `RunUsage`, and `UsageLimits` to specify that only successful tool calls are counted and to clarify the meaning of usage limits.

Author: tradeqvest

pydantic_ai_slim/pydantic_ai/_run_context.py

@@ -50,6 +50,6 @@ class RunContext(Generic[AgentDepsT]):
     tool_call_approved: bool = False
     """Whether a tool call that required approval has now been approved."""
     usage_limits: UsageLimits | None = None
-    """Usage limits for this run, if any."""
+    """Usage limits for the run."""
 
     __repr__ = _utils.dataclasses_no_defaults_repr

pydantic_ai_slim/pydantic_ai/usage.py

@@ -118,7 +118,7 @@ class RunUsage(UsageBase):
     """Number of requests made to the LLM API."""
 
     tool_calls: int = 0
-    """Number of tool calls executed during the run."""
+    """Number of successful tool calls executed during the run."""
 
     input_tokens: int = 0
     """Total number of text input/prompt tokens."""
@@ -197,7 +197,7 @@ class UsageLimits:
     request_limit: int | None = 50
     """The maximum number of requests allowed to the model."""
     tool_calls_limit: int | None = None
-    """The maximum number of tool calls allowed to be executed."""
+    """The maximum number of successful tool calls allowed to be executed."""
     input_tokens_limit: int | None = None
     """The maximum number of input/prompt tokens allowed."""
     output_tokens_limit: int | None = None