fix(langchain): Fix strict pylance error on tool decorator import

[le-codeur-rapide]

Description

Fixes #33019 by improving type hints for the tool decorator

This PR only modify type hints so no behaviour changes are expected.

[vercel]

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
langchain	Ignored	Preview		Sep 19, 2025 1:36pm

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #33020 will not alter performance

_{Comparing le-codeur-rapide:langchain_fix_strict_typing_tool_decorator (b347c02) with master (90280d1)¹}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 13 untouched

Footnotes

1. No successful run was found on master (4d11877) during the generation of this report, so 90280d1 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩