Steers custom tool creation toward the plugin route by default.
The adding-tools.md guide is now explicitly for built-in core Hermes
tools only.
Key fixes:
- Plugin quickstart: ctx.register_tool() now uses correct keyword-arg
API (name=, toolset=, schema=, handler=) instead of broken 3-arg call
- Handler signature: (params, **kwargs) instead of (params)
- Handler return: json.dumps({...}) instead of plain string
- AGENTS.md: mentions plugin route before built-in tool instructions
- learning-path.md: plugins listed before core tool development
- contributing.md: separates plugin vs core tool paths
Based on PR #13138 by @helix4u.
eeb05cf556