Rhino MCP

[RHINO_MCP]

rhino-mcp-platform, a USER-scope stdio server in ~/.claude.json running the rhino-mcp-router binary, proxies each mcp__rhino-mcp-platform__* call to a per-document loopback HTTP listener inside the targeted Rhino "slot". Every document-touching tool binds to that slot's RhinoDoc, never RhinoDoc.ActiveDoc. All outputs are JSON strings (viewport adds a JPEG block). The router runs directly on the client's stdio pipe: it spawns a Rhino host on demand, adopts a user-started session through its slot lifecycle, and exits on client disconnect.

forge-rhino-up (idempotent, splash-free) brings up a visible Rhino the router adopts.

[01]-[SLOT_LIFECYCLE]

Every non-router tool accepts an implicit slot arg (animal-name ID). Omitting it uses the last-used/open Rhino, auto-spawning one only if none is running. Slot state is lazy and stateful — list_slots is what prunes crashed Rhinos and adopts user-started ones since the last call.

• close_slot: stops listener, closes doc, saves none; error.code ∈ slot_not_found, cannot_close_adopted.

[IMPORTANT] Poll list_slots before assuming a held slot is live. Adopted (user-started) slots return cannot_close_adopted and are non-disposable — treat them as borrowed, never force-close them.

[02]-[SCRIPTING]-[RUN_CSHARP_PYTHON_COMMAND]

Scripting is the universal escape hatch: full RhinoCommon scoped to the slot's doc, stdout/error captured.

[IMPORTANT] run_csharp evaluates a STATEMENT BODY, not an expression — a top-level return <expr>; is rejected. Emit results through Console.WriteLine(...); never write an expression-returning lambda.

[IMPORTANT] Both scripting tools inject __rhino_doc__ (the slot's RhinoDoc). Use it directly. In Python do NOT use scriptcontext.doc or rhinoscriptsyntax's implicit doc — they bind to the wrong document. In C# operate on __rhino_doc__.

[IMPORTANT] error: null is necessary but NOT sufficient for success: error detection is heuristic string-matching (Traceback, error CS, Compile Error, Exception:) over scraped command-window text, so a silent failure or a no-op can read as success. Assert post-conditions explicitly — re-query g2_get_canvas_graph / list_objects / the written .3dm — rather than trusting a null error. Capture is fire-and-harvest, not streaming: always print / Console.WriteLine explicit, self-serialized structured results; never rely on return-value capture. run_command hard-blocks if a prior command awaits interactive input — prefer scripting over run_command for any non-trivial geometry to avoid stranding a slot in an interactive prompt.

[03]-[DOCUMENT_IO]

Headless, no dialogs. All bound to the slot's doc.

[04]-[SCENE_QUERY_SELECTION_MATERIALS]

[SCENE_QUERY_SHAPES]:

• Filters: names[]?, layer?, geometryType?, includeHidden=false, includeLocked=true, limit=1000.
• Object item: {id, name, layer, type}.
• Selection write: ids[]?, names[]?, layer?, and geometryType? select a union after clearing current selection.
• Material write: layer, color?, transparency? 0-1, gloss? 0-1, and applyToLayerColor=true.
• geometryType vocabulary: point, pointset, curve, surface, brep, mesh, annotation, light, block.

[05]-[VIEWPORT_AND_CAMERA]

[VIEWPORT_CAPTURE_SHAPE]:

• Size: width=480 up to 1280, height=270 up to 720.
• Frame inputs: view?, displayMode?, cameraLocation?, target?, boxMin?/boxMax?, zoom?.
• Output: JSON metadata and JPEG when the scene is renderable; metadata-only diagnostic when empty or off-screen.
• Camera write: location?, target?, up?, lensLength?, projection?, and boxMin?/boxMax?; bbox framing applies last.

[IMPORTANT] On an empty/off-screen capture, read scene.boundingBox and object counts before re-framing with boxMin/boxMax or view. Every JPEG block costs context tokens: capture at the minimum resolution sufficient to diagnose, keep the 480x270 default first, and escalate toward the 1280x720 ceiling only after a metadata-only pass.

[06]-[GRASSHOPPER]-[GRAPH_AUTHORING_G2]

g2_* is the Grasshopper graph-authoring surface for Rasm MCP work. It authors Grasshopper2 canvas and document objects through McNeel's interactive MCP platform.

[GH_KERNEL_RULES]:

• Solve: mutating GH2 tools accept solve=true; set solve=false while batching and solve once after the batch.
• Explicit solve: use g2_solve_canvas for solve/status readback.
• Slider policy: GH2 sliders use decimals 0..12; 0 gives integer behavior.

[GH_COMPONENT_SHAPES]:

• Component search: query, category?, subcategory?, and limit=20 return Guid, Name, Category, SubCategory, Kind, and Description.
• Component ports: g2_describe_component returns Inputs[]/Outputs[]: Name, UserName, Description, TypeName, Access, Requirement.

Discovery operations use GH2 component lookup and port-inspection tools:

Placement operations create canvas objects from component and slider inputs:

[GH_GRAPH_BATCH_SHAPE]:

• Component placement: selector prefers Guid; x=100, y=100, and solve=true are default placement inputs.
• Slider placement: min, value, max, x, y, decimals, solve, and name? define the slider.
• Batch apply: g2_apply_graph accepts sliders[], components[] with caller Key, wires[] with SrcKey/DstKey, and solve=true.
• Batch output: g2_apply_graph returns Placed[], PlaceErrors[], Wires[], and WiresOk without aborting on per-step failures.

Wiring and solving operations connect objects, apply batches, and resolve the canvas:

[GH_CANVAS_READBACK_SHAPE]:

• Canvas readback: g2_get_canvas_graph accepts include_data=true and sample_size=3.
• Canvas payload: readback returns Objects[] and Wires[]; records carry Messages[], input Sources[], data summaries, slider DisplaySummary.
• Canvas cleanup: g2_clear_canvas requires confirm=true and accepts solve=true.

Inspection and cleanup operations read or clear the current canvas:

[IMPORTANT] Prefer selector by Guid from g2_search_components; a name match returning multiple candidates yields {Error:"ambiguous", Candidates[]}. Call g2_describe_component before placing or wiring to learn input and output ports. For closed-loop iteration, read back g2_get_canvas_graph because object Messages[] carry per-component warnings/errors and slider DisplaySummary carries computed values. Use g2_apply_graph to build a whole definition in one call; g2_connect and g2_connect_many accept numeric index, Name, UserName, or DisplayName for ports, and "" or "0" for pure params such as sliders.