fix: allowed_tools=[] treated as falsy instead of disabling all tools#524
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drillan wants to merge 1 commit intoanthropics:mainfrom
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fix: allowed_tools=[] treated as falsy instead of disabling all tools#524drillan wants to merge 1 commit intoanthropics:mainfrom
drillan wants to merge 1 commit intoanthropics:mainfrom
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…ll tools `allowed_tools=[]` was treated as falsy and ignored, causing all tools to remain available instead of none. Change the default from `[]` to `None` and use `is not None` check to correctly pass `--allowedTools ""` to the CLI when an empty list is explicitly provided. Fixes anthropics#523 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
allowed_tools=[](explicitly empty) andallowed_tools=None(unset) were indistinguishable due to Python's truthiness check on empty lists--allowedToolscontrols which tools execute without prompting for permission (auto-allow list), not which tools are available (that's--tools)allowed_tools=[]should mean "no tools are auto-allowed (all require permission prompting)", but was silently ignored, leaving the default permission behavior unchangedChanges
allowed_toolsdefault from[]toNoneinClaudeAgentOptionsto distinguish "unset" from "explicitly empty"is not Noneinsubprocess_cli.pysoallowed_tools=[]correctly passes--allowedTools ""to the CLIClarification
This fix addresses the
Nonevs[]conflation bug. Note that--allowedToolsis about permission prompting behavior, not tool availability:None--allowedToolsomitted[]--allowedTools ""["Read", "Bash(git *)"]--allowedTools "Read,Bash(git *)"To restrict which tools are available to the model, use the
toolsoption (--tools) instead.Fixes #523
Test plan
python -m pytest tests/test_transport.py -k allowed_tools— 2 new tests passpython -m pytest tests/test_types.py— updated default assertion passespython -m pytest tests/— all tests passpython -m mypy src/— no errors🤖 Generated with Claude Code