Summary
Add focused regression coverage for a ToolInvoker/Agent tool that completes successfully while returning an empty or otherwise falsy result.
Current implementation facts
Haystack's Agent tool flow distinguishes tool execution from message conversion.
Problem
An empty string, list, or dictionary can be treated differently from a non-empty result by downstream message construction. A change can accidentally turn a successful empty result into a missing result or error.
Scope
- Add parameterized tests for supported empty result shapes.
- Assert emitted status and tool-call correlation.
- Cover sync and async paths where available.
Non-goals
- Do not define a new display format.
- Do not change semantics without maintainer agreement.
Acceptance criteria
- Empty results remain successful tool results.
- Tool-call identifiers remain attached.
- Existing result tests pass.
I searched Haystack issues and PRs for ToolInvoker, empty tool result, and falsy result handling before filing this proposal.
Summary
Add focused regression coverage for a ToolInvoker/Agent tool that completes successfully while returning an empty or otherwise falsy result.
Current implementation facts
Haystack's Agent tool flow distinguishes tool execution from message conversion.
Problem
An empty string, list, or dictionary can be treated differently from a non-empty result by downstream message construction. A change can accidentally turn a successful empty result into a missing result or error.
Scope
Non-goals
Acceptance criteria
I searched Haystack issues and PRs for ToolInvoker, empty tool result, and falsy result handling before filing this proposal.