fix(HTTP Request Tool Node): Prevent creation of DynamicStructuredTool with empty schema

[OlegIvaniv]

Summary

When using the HTTP Request Tool without any placeholders, an empty arguments schema was being generated. This caused compatibility issues with certain LLM providers (like Gemini) that enforce strict API validation requirements for tool schemas.

Solution

Added a condition to check if the HTTP Request Tool has any parameters (placeholders) defined:

• If toolParameters.length > 0: Use N8nTool with the generated schema
• If toolParameters.length === 0: Fall back to using DynamicTool without a schema

Related Linear tickets, Github issues, and Community forum posts

• Gemini Tools Agent Not Working #12109

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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