export_voxel_modelCreate direct download URLs for OBJ+MTL or compact VoxelDraft JSON from a modelRef.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | obj | |
| modelRef | Yes | Short temporary VoxelDraft model reference returned by model tools |
Changes observed during successful MCP inspections.
Input schema / properties / modelRef / descriptionPrevious value: -"Short temporary VoxelDraft model reference that expires after 7 days of inactivity"New value: +"Short temporary VoxelDraft model reference returned by model tools"Output schema / (root)Previous value: -{
- "oneOf": [
- {
- "additionalProperties": false,
- "properties": {
- "downloadUrl": {
- "format": "uri",
- "type": "string"
- },
- "format": {
- "const": "VoxelDraft compact JSON",
- "type": "string"
- },
- "stats": {
- "additionalProperties": false,
- "properties": {
- "bounds": {
- "anyOf": [
- {
- "type": "null"
- },
- {
- "additionalProperties": false,
- "properties": {
- "max": {
- "items": {
- "maximum": 63,
- "minimum": 0,
- "type": "integer"
- },
- "maxItems": 3,
- "minItems": 3,
- "type": "array"
- },
- "min": {
- "items": {
- "maximum": 63,
- "minimum": 0,
- "type": "integer"
- },
- "maxItems": 3,
- "minItems": 3,
- "type": "array"
- },
- "size": {
- "items": {
- "maximum": 64,
- "minimum": 1,
- "type": "integer"
- },
- "maxItems": 3,
- "minItems": 3,
- "type": "array"
- }
- },
- "required": [
- "min",
- "max",
- "size"
- ],
- "type": "object"
- }
- ]
- },
- "colors": {
- "items": {
- "pattern": "^#[0-9a-fA-F]{6}$",
- "type": "string"
- },
- "maxItems": 512,
- "type": "array"
- },
- "commandCount": {
- "maximum": 512,
- "minimum": 0,
- "type": "integer"
- },
- "voxelCount": {
- "maximum": 100000,
- "minimum": 0,
- "type": "integer"
- }
- },
- "required": [
- "voxelCount",
- "commandCount",
- "colors",
- "bounds"
- ],
- "type": "object"
- }
- },
- "required": [
- "format",
- "downloadUrl",
- "stats"
- ],
- "type": "object"
- },
- {
- "additionalProperties": false,
- "properties": {
- "format": {
- "const": "OBJ+MTL",
- "type": "string"
- },
- "mtlUrl": {
- "format": "uri",
- "type": "string"
- },
- "objUrl": {
- "format": "uri",
- "type": "string"
- },
- "optimization": {
- "additionalProperties": false,
- "properties": {
- "materialCount": {
- "minimum": 0,
- "type": "integer"
- },
- "vertexCount": {
- "minimum": 0,
- "type": "integer"
- },
- "visibleFaceCount": {
- "minimum": 0,
- "type": "integer"
- },
- "voxelCount": {
- "minimum": 0,
- "type": "integer"
- }
- },
- "required": [
- "voxelCount",
- "vertexCount",
- "visibleFaceCount",
- "materialCount"
- ],
- "type": "object"
- }
- },
- "required": [
- "format",
- "objUrl",
- "mtlUrl",
- "optimization"
- ],
- "type": "object"
- }
- ],
- "type": "object"
-}New value: +nullInput schema / properties / modelRemoved value: -{
- "type": "string"
-}Input schema / properties / modelRefAdded value: +{
+ "description": "Short temporary VoxelDraft model reference that expires after 7 days of inactivity",
+ "maxLength": 64,
+ "type": "string"
+}Input schema / requiredPrevious value: -[
- "model"
-]New value: +[
+ "modelRef"
+]Output schema / (root)Previous value: -nullNew value: +{
+ "oneOf": [
+ {
+ "additionalProperties": false,
+ "properties": {
+ "downloadUrl": {
+ "format": "uri",
+ "type": "string"
+ },
+ "format": {
+ "const": "VoxelDraft compact JSON",
+ "type": "string"
+ },
+ "stats": {
+ "additionalProperties": false,
+ "properties": {
+ "bounds": {
+ "anyOf": [
+ {
+ "type": "null"
+ },
+ {
+ "additionalProperties": false,
+ "properties": {
+ "max": {
+ "items": {
+ "maximum": 63,
+ "minimum": 0,
+ "type": "integer"
+ },
+ "maxItems": 3,
+ "minItems": 3,
+ "type": "array"
+ },
+ "min": {
+ "items": {
+ "maximum": 63,
+ "minimum": 0,
+ "type": "integer"
+ },
+ "maxItems": 3,
+ "minItems": 3,
+ "type": "array"
+ },
+ "size": {
+ "items": {
+ "maximum": 64,
+ "minimum": 1,
+ "type": "integer"
+ },
+ "maxItems": 3,
+ "minItems": 3,
+ "type": "array"
+ }
+ },
+ "required": [
+ "min",
+ "max",
+ "size"
+ ],
+ "type": "object"
+ }
+ ]
+ },
+ "colors": {
+ "items": {
+ "pattern": "^#[0-9a-fA-F]{6}$",
+ "type": "string"
+ },
+ "maxItems": 512,
+ "type": "array"
+ },
+ "commandCount": {
+ "maximum": 512,
+ "minimum": 0,
+ "type": "integer"
+ },
+ "voxelCount": {
+ "maximum": 100000,
+ "minimum": 0,
+ "type": "integer"
+ }
+ },
+ "required": [
+ "voxelCount",
+ "commandCount",
+ "colors",
+ "bounds"
+ ],
+ "type": "object"
+ }
+ },
+ "required": [
+ "format",
+ "downloadUrl",
+ "stats"
+ ],
+ "type": "object"
+ },
+ {
+ "additionalProperties": false,
+ "properties": {
+ "format": {
+ "const": "OBJ+MTL",
+ "type": "string"
+ },
+ "mtlUrl": {
+ "format": "uri",
+ "type": "string"
+ },
+ "objUrl": {
+ "format": "uri",
+ "type": "string"
+ },
+ "optimization": {
+ "additionalProperties": false,
+ "properties": {
+ "materialCount": {
+ "minimum": 0,
+ "type": "integer"
+ },
+ "vertexCount": {
+ "minimum": 0,
+ "type": "integer"
+ },
+ "visibleFaceCount": {
+ "minimum": 0,
+ "type": "integer"
+ },
+ "voxelCount": {
+ "minimum": 0,
+ "type": "integer"
+ }
+ },
+ "required": [
+ "voxelCount",
+ "vertexCount",
+ "visibleFaceCount",
+ "materialCount"
+ ],
+ "type": "object"
+ }
+ },
+ "required": [
+ "format",
+ "objUrl",
+ "mtlUrl",
+ "optimization"
+ ],
+ "type": "object"
+ }
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare non-destructive, non-open-world operation with readOnlyHint=false, which fits an operation that mints URLs. The description adds that the result is 'direct download URLs' and that OBJ exports include an MTL companion, but it omits URL lifetime/expiry, whether multiple URLs are returned, or any auth/size constraints.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single front-loaded sentence with no filler; the action, the outputs, and the key input (modelRef) all appear immediately.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
There is no output schema, so the description must convey the return value, and it does — download URLs. For a 2-parameter tool this is nearly sufficient, with only URL validity and cardinality left unspecified.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is only 50%: modelRef is documented in the schema, format is not. The description compensates by explaining what each format value yields ('OBJ+MTL' vs 'compact VoxelDraft JSON'), which adds real meaning beyond the bare obj/json enum.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a concrete verb+resource: it creates direct download URLs for a voxel model, and names the two output formats (OBJ+MTL, compact VoxelDraft JSON). This is distinct from siblings like save_voxel_model or render_voxel_model, though the description never explicitly contrasts them.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is only implied by the verb 'export' and the input requirement of a modelRef. There is no explicit statement of when to prefer this over save_voxel_model or render_voxel_model, nor any exclusions or prerequisites beyond the schema's note that modelRef comes from model tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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