Add scene context resource and get_object_info tool

[mien-bot]

Summary

• Scene context resource (rhino://scene-context): Exposes current document state (units, tolerances, layer tree with object counts, type breakdown, and scene bounding box) as a read-only MCP resource. Gives AI agents the context they need before creating or modifying geometry.
• get_object_info tool: Returns detailed information for a single object by GUID — bounding box, layer, visibility, and type-specific metrics (area/volume for breps, vertex/face count for meshes, length/degree for curves).

Both follow existing patterns: InvokeAndWait for thread safety, System.Text.Json serialization, DI-injected RhinoDoc.

Test plan

• Load plugin in Rhino 8, run RhinoMCP to start server
• Verify scene_context resource appears in resource list and returns valid JSON
• Create some objects, confirm resource reflects correct counts/layers/bbox
• Call get_object_info with a valid GUID, verify metrics are returned
• Call get_object_info with invalid GUID, verify error response

Note: Build-verified only — I don't have Rhino 8 to runtime test. Happy to iterate on feedback.

[mien-bot]

Hey! I've been building an MCP integration for Rhino on my own project and noticed this repo doesn't have any MCP resources yet. Thought a scene context resource would be a natural first one — agents really benefit from knowing document state (units, layers, what's in the scene) before they start creating geometry.

Also added a get_object_info tool since list_objects gives the overview but there's no way to drill into a specific object's metrics.

I only have Rhino 7 so I couldn't runtime test, but everything compiles clean and follows the existing patterns. Let me know if you'd like any changes!

[clicky]

Hey @mien-bot do you publish your MCP integration on GitHub or elsewhere? I'd be curious to take a look. I'm still learning and reading about Resources but am trying to see what claude naturally reaches for when creating things

[mien-bot]

@clicky Yeah! I created my own rhino mcp plugin in a private repo, but the plugin is called Aurox which his similar MCP features. I was focusing on making it as easy as possible for users to install MCP functionality either through the Claude desktop app, CLI mode, or API integration. I just thought I'd contribute a bit, since with get context claude would have a better understanding of what's in the scene and what scale and the units of the objects.