Description

Some background context:

Bedrock rejects tool names that are invalid (e.g. they don't match this regex) and so if the LLM generates an invalid name, we need to replace that name before sending to Bedrock as otherwise bedrock throws an error message

This is the follow up to the first pr (#1087) and is a 2nd part fix to #1069.

Per the bug, session-managers never persist tool-name changes after the initial persisting of the message, which means once an agent generates an invalid-tool name, that message history is poisoned on re-hydration. To avoid that going forward, do the translation of invalid-tool names on sending to the provider and not on the initial tool_use detection. The initial tool_use detection is still needed to add a tool_response with a proper error message for the LLM, but the tool name change is now done elsewhere to avoid the poisoning issue

Previous behavior

Prior to both bug fixes, this was the problem:

1. The LLM generates a toolUse block for a tool that has an invalid name (specifically it doesn't match this regex)
2. The message with the toolUse is appended to the agent's history.
3. Tool execution begins - first in event_loop._handle_tool_execution which calls validate_and_prepare_tools is invoked. The validation fails which has two side-effects:
   1. The original/invalid tool name is overwritten with INVALID_TOOL_NAME
      1. BUG # 2 -- The tool name overrwrite is not persisted to the session-manager because we don't do updates to existing messages
   2. A tool-result is added indicating the invalidness of the tool-name
4. We early exit out of tool execution because there are no tool-uses
   1. BUG # 1 -- At this point, the loop should continue as normal and pass flow back to the model, but we're not doing that here

Bug # 1 was fixed in #1087, and this is now the fix for Bug # 2

Notes

• I added an integ test that fails before the changes and succeeds after
• I also refactored a bunch of validation methods to make them internal, deprecating the old public methods

Related Issues

#1069

Documentation PR

N/A

Type of Change

Bug fix

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

• I ran hatch run prepare

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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