strands.types.event_loop

Event loop-related type definitions for the SDK.

Usage

class Usage(TypedDict)

Defined in: src/strands/types/event_loop.py:8

Token usage information for model interactions.

Attributes:

• inputTokens - Number of tokens sent in the request to the model.
• outputTokens - Number of tokens that the model generated for the request.
• totalTokens - Total number of tokens (input + output).
• cacheReadInputTokens - Number of tokens read from cache (optional).
• cacheWriteInputTokens - Number of tokens written to cache (optional).

Metrics

class Metrics(TypedDict)

Defined in: src/strands/types/event_loop.py:26

Performance metrics for model interactions.

Attributes:

• latencyMs int - Latency of the model request in milliseconds.
• timeToFirstByteMs int - Latency from sending model request to first content chunk (contentBlockDelta or contentBlockStart) from the model in milliseconds.

StopReason

Reason for the model ending its response generation.

• “content_filtered”: Content was filtered due to policy violation
• “end_turn”: Normal completion of the response
• “guardrail_intervened”: Guardrail system intervened
• “interrupt”: Agent was interrupted for human input
• “max_tokens”: Maximum token limit reached
• “stop_sequence”: Stop sequence encountered
• “tool_use”: Model requested to use a tool