[FEATURE] Hooks - Events - BeforeToolsEvent and AfterToolsEvent

[pgrayy]

Problem Statement

I would like the Python SDK to support a BeforeToolsEvent and AfterToolsEvent for parity with the TypeScript SDK (docs).

• BeforeToolsEvent: Triggered before tools are executed in a batch.
• AfterToolsEvent: Triggered after tools are executed in a batch. Uses reverse callback ordering.

Proposed Solution

No response

Use Case

An example use case would be for requesting approval on a batch of tool calls through the interrupt mechanism.

Alternatives Solutions

No response

Additional Context

No response

[strands-agent]

I've implemented BeforeToolsEvent and AfterToolsEvent following the existing hook patterns in the SDK. The implementation is complete with:

Events Added (src/strands/hooks/events.py)

BeforeToolsEvent

• Inherits HookEvent + _Interruptible
• tool_uses: list[ToolUse] - batch of pending tool calls
• cancel_tools: bool | str = False - cancel the entire batch
• Supports interrupt pattern for batch approval

AfterToolsEvent

• Inherits HookEvent
• tool_uses: list[ToolUse] - executed tool calls
• results: list[ToolResult] - results from all tools
• should_reverse_callbacks = True (cleanup semantics)

Stream Events Added (src/strands/types/_events.py)

• ToolsCancelEvent - emitted when batch is cancelled
• ToolsInterruptEvent - emitted when batch is interrupted

Integration (src/strands/event_loop/event_loop.py)

• BeforeToolsEvent fires before tool_executor._execute()
• AfterToolsEvent fires after all tools complete
• Full support for cancel_tools and interrupt patterns

Tests Added (tests_integ/hooks/test_tools_events.py)

• Event emission verification
• Callback ordering (reverse for AfterToolsEvent)
• Cancel tools functionality
• Interrupt handling

I'm encountering a PAT token scope issue when pushing to my fork (the workflow scope is needed due to .github/workflows/LAMDBA_LAYERS_SOP.md). Would a maintainer be able to help merge this, or should I open a draft PR with the patch contents?

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[zastrowm]

A rough draft of this feature is in zastrowm#26 though it needs to be shepherded the rest of the way through