fix(tools): raise ToolUsageError instead of bare raise for non-dict arguments

[nolanchic]

Description

ToolUsage._original_tool_calling() used a bare raise outside any active except block when the parsed tool arguments were not a dict:

if not isinstance(arguments, dict):
    if raise_error:
        raise          # <- no active exception here
    return ToolUsageError(...)

A bare raise re-raises the exception currently being handled, but on this path the preceding try/except completed normally, so no exception is active. Result: with raise_error=True the call raised RuntimeError: No active exception to reraise instead of the intended ToolUsageError, masking the real tool-arguments problem.

Fix: raise the explicit ToolUsageError, matching the message already used by the raise_error=False branch on the next line.

if not isinstance(arguments, dict):
    if raise_error:
        raise ToolUsageError(f"{I18N_DEFAULT.errors('tool_arguments_error')}")
    return ToolUsageError(f"{I18N_DEFAULT.errors('tool_arguments_error')}")

Why the bug was latent

_validate_tool_input() currently always returns a dict or raises, so the non-dict branch was effectively dead code in normal use. The bug surfaces whenever that contract is relaxed — e.g. subclasses overriding _validate_tool_input, monkeypatching in tests, or future changes to the validation pipeline. Making the branch raise the correct exception keeps the failure mode meaningful instead of an opaque RuntimeError.

Test plan

• Added regression test test_original_tool_calling_raises_tool_usage_error_for_non_dict_arguments — fails with RuntimeError on the old code, passes with ToolUsageError after the fix.
• Added test_original_tool_calling_returns_tool_usage_error_for_non_dict_without_raise covering the raise_error=False path.
• uv run pytest lib/crewai/tests/tools/ → 135 passed.
• uv run ruff check lib/ → clean.
• uv run mypy lib/crewai/src/crewai/tools/tool_usage.py → clean (strict).

Fixes #6430.

Note: per .github/CONTRIBUTING.md, this PR is authored by an AI agent (Claude Code) and carries the llm-generated label.

[coderabbitai]

📝 Walkthrough

Walkthrough

Fixed a bare raise statement in ToolUsage._original_tool_calling that caused a RuntimeError when raise_error=True and tool input validation returned a non-dict value. The method now raises ToolUsageError with the existing error message. Added regression tests covering both raise_error states.

Changes

Bare raise fix and regression tests

Layer / File(s)	Summary
Raise ToolUsageError instead of bare raise lib/crewai/src/crewai/tools/tool_usage.py	When raise_error=True and validated tool input is not a dict, raises ToolUsageError(tool_arguments_error) instead of re-raising a nonexistent active exception.
Regression tests for both raise_error paths lib/crewai/tests/tools/test_tool_usage.py	Imports ToolUsageError, adds tests asserting raise_error=True raises ToolUsageError and raise_error=False returns a ToolUsageError instance.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main fix: replacing a bare raise with ToolUsageError for non-dict tool arguments.
Description check	✅ Passed	The description is directly related to the code change and regression tests in this pull request.
Linked Issues check	✅ Passed	The change matches #6430 by raising ToolUsageError with the existing message and adding regression tests for both paths.
Out of Scope Changes check	✅ Passed	The PR stays focused on the bug fix and related tests, with no unrelated changes evident.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

lib/crewai/tests/tools/test_tool_usage.py (1)

562-587: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Consider asserting the error message in the raise_error=True test.

The PR objectives mention verifying "corrected exception type and message," but pytest.raises(ToolUsageError) only checks the type. Adding a match= parameter would also confirm the i18n tool_arguments_error message is surfaced, strengthening the regression test against future changes that might raise a different ToolUsageError.

♻️ Proposed fix to assert the error message

-            with pytest.raises(ToolUsageError):
+            with pytest.raises(ToolUsageError, match="not a valid key, value dictionary"):
                tool_usage._original_tool_calling("tool_string", raise_error=True)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/crewai/tests/tools/test_tool_usage.py` around lines 562 - 587, The
regression test for ToolUsage._original_tool_calling currently only checks that
ToolUsageError is raised; update the assertion in
test_original_tool_calling_raises_tool_usage_error_for_non_dict_arguments to
also verify the exception message with pytest.raises(..., match=...) so it
confirms the i18n tool_arguments_error text is emitted when raise_error=True.
Keep the existing mock setup and patching around _select_tool and
_validate_tool_input, and strengthen the test so it validates both the exception
type and message.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@lib/crewai/tests/tools/test_tool_usage.py`:
- Around line 562-587: The regression test for ToolUsage._original_tool_calling
currently only checks that ToolUsageError is raised; update the assertion in
test_original_tool_calling_raises_tool_usage_error_for_non_dict_arguments to
also verify the exception message with pytest.raises(..., match=...) so it
confirms the i18n tool_arguments_error text is emitted when raise_error=True.
Keep the existing mock setup and patching around _select_tool and
_validate_tool_input, and strengthen the test so it validates both the exception
type and message.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: bec184db-fdeb-49c6-8049-6766e0a9a424

📥 Commits

Reviewing files that changed from the base of the PR and between 289686a and 0b8e831.

📒 Files selected for processing (2)

• lib/crewai/src/crewai/tools/tool_usage.py
• lib/crewai/tests/tools/test_tool_usage.py