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Add a mesh

bb_add_mesh

Add a custom mesh to a Blockbench model by defining vertices and faces, with optional UVs and textures for detailed geometry.

Instructions

Create a free-form mesh. vertices is a list of [x,y,z] (or a {key:[x,y,z]} map). faces is a list where each face is either [i0,i1,i2] indices into vertices, or {vertices:[i..], uv:[[u,v]..], texture}. UVs are stored per vertex.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameNo
facesYes
originNo
parentNo
textureNo
rotationNo
verticesYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv2.0.0

TDQS

B3.2/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations, so the description carries the full burden. It does usefully disclose the internal data formats (per-vertex UVs, keyed vertex maps, face variants), which is real behavioral value. However, it says nothing about edit-mode requirements, permissions, return values, or what happens to any existing mesh.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences with the core action front-loaded, then format detail. No filler. Slightly dense prose but every clause carries information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 7-parameter mutation tool with no annotations and no output schema, the description covers the two critical data-format params well but leaves the remaining five params and all behavioral aspects (mode, side effects, return) unexplained.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0% and the schema for vertices/faces is empty ({}), so the description genuinely compensates by fully specifying those two formats — a real contribution. But five parameters (name, origin, parent, texture, rotation) are undocumented in both the schema and the description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource: 'Create a free-form mesh.' The word 'free-form' implicitly separates it from bb_add_cube, but it never names that or any sibling explicitly, so the distinction is left for the agent to infer.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No when-to-use guidance at all. With siblings like bb_add_cube, bb_add_element, and bb_edit_mesh available, the description should say when a free-form mesh is preferred, but it offers nothing about context or alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.