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tool_execute_before hook cannot modify tool arguments (mutated args not re-read) #1926
Description
- Problem: Extensions hooking
tool_execute_before(extensions/python) mutate tool kwargs (e.g., sanitizing or expanding placeholders in tool inputs), but the framework invokes the tool with the ORIGINAL arguments — the mutated kwargs are never re-assigned after the hook completes. This makes argument transformation hooks impossible without core edits. - Reproduction: Register a
tool_execute_beforeextension that changes a tool's args; the executed tool receives the pre-hook values. - Proposed fix: Re-assign the mutated arguments after the
tool_execute_beforehook chain runs (one line:tool.args = tool_args/ equivalent re-read of hook output). We run this as a local patch in production (fork commit d7ed0ef) since 2026-09 with no regressions. - Offer: Happy to open a PR if the direction is accepted.
Activity
fix: v2.13-compatible blocking, path-scoped matching, fail-open evalu…
Li-john1021 commentedon Oct 14, 2026
你好，我想认领这个问题。
已核对：
tool_execute_before在_execute_tool_request/process_tools/execute_tool_call（parallel）三处调用后，未把 hook 可能就地修改过的tool_args再写回tool.args。不少工具（以及 MCP 工具初始args={}）会读self.args，因此会出现 hook 已改、执行仍用旧值的分叉。计划按 issue 建议做最小修复：hook 链结束后补上
tool.args = tool_args，并加回归测试覆盖两条主 dispatch 路径。若已有他人在推进，请告诉我，我这边先停下。