Unity FBX Import with Full URLs

This skill ensures that when importing external 3D models (FBX files) into Unity using the Unity MCP

Unity_ImportExternalModel

tool, full and complete URLs are always provided, preventing import failures due to incomplete paths.

When to use this skill

Use this skill automatically whenever:

Importing FBX files from external sources
Adding 3D models to the Unity project
Loading assets from URLs or file paths
User mentions: "import model", "add FBX", "load 3D asset", "bring in model"
Using the
```
Unity_ImportExternalModel
```
tool from Unity MCP

Core principle

ALWAYS use complete, fully-qualified URLs for FBX files.

Never use relative paths, partial URLs, or assume path completion. The

FbxUrl

parameter must be a complete URL or absolute file path.

Instructions

Step 1: Identify the FBX source

When a user requests to import a model, determine the source:

Remote URL (HTTP/HTTPS):
- Must start with
```
http://
```
  or
```
https://
```
- Must include the full domain and path
- Filename must end with
```
.fbx
```
  or
```
.zip
```
- IMPORTANT: Include ALL query parameters and tokens after the extension
- Query parameters (like
```
?param=value&other=data
```
  ) are required for authentication
- Example:
```
https://example.com/models/character.fbx?token=abc123&auth=xyz
```
- Example:
```
https://cdn.fbcdn.net/path/file.fbx?_nc_gid=xxx&_nc_oc=yyy&oh=zzz
```
Local file (file system):
- Must be an absolute path (not relative)
- Windows:
```
C:/Users/name/Downloads/model.fbx
```
- Unix/Mac:
```
/home/user/models/model.fbx
```
- Must end with
```
.fbx
```
  or
```
.zip
```
ZIP archive:
- Can be URL or local path
- Must contain an FBX file inside
- Example:
```
https://example.com/assets.zip
```

Step 2: Validate the URL format

Before calling

Unity_ImportExternalModel

, verify the URL:

CRITICAL: For URLs with query parameters (like

?token=...&auth=...

), you MUST include the ENTIRE URL including all parameters. Query parameters often contain authentication tokens required for download.

Valid examples:

https://cdn.example.com/assets/models/chair.fbx

https://cdn.example.com/models/chair.fbx?token=abc123&auth=xyz789

(with query params)

https://scontent.fbcdn.net/model.fbx?_nc_gid=xxx&_nc_oc=yyy&oh=zzz

(Meta CDN with auth)

http://localhost:8000/models/character.fbx

file:///C:/Users/name/Downloads/robot.fbx

```
C:/Projects/Models/tree.fbx
```
(Windows absolute)
```
/home/user/assets/car.fbx
```
(Unix absolute)

https://github.com/user/repo/releases/download/v1.0/model.zip

Invalid examples (never use these):

```
models/chair.fbx
```
(relative path)
```
~/Downloads/robot.fbx
```
(tilde expansion not supported)
```
example.com/model.fbx
```
(missing protocol)
```
../assets/model.fbx
```
(relative path)
```
model.fbx
```
(no path at all)

Step 3: Get required parameters

The

Unity_ImportExternalModel

tool requires:

Name (required):
- Simple identifier (single word, no spaces)
- Use alphanumeric characters and underscores/hyphens
- Example:
```
office_chair
```
  ,
```
character_01
```
  ,
```
tree_oak
```
FbxUrl (required):
- MUST be a complete, full URL or absolute path
- No relative paths allowed
- Include protocol for remote URLs (
```
http://
```
  ,
```
https://
```
  )
Height (required):
- Desired height in Unity units (meters)
- Reasonable values: 0.1 to 10.0 for most objects
- Example: 1.8 for human-sized character, 2.0 for chair
AlbedoTextureUrl (optional):
- Full URL to texture file (same rules as FbxUrl)
- Can be local file or remote URL
- Common formats:
```
.png
```
  ,
```
.jpg
```
  ,
```
.jpeg
```

Step 4: Call Unity_ImportExternalModel with full URL

Use the Unity MCP tool with complete parameters:

json

{
  "Name": "office_chair",
  "FbxUrl": "https://example.com/models/office_chair.fbx",
  "Height": 1.0,
  "AlbedoTextureUrl": "https://example.com/textures/chair_diffuse.png"
}

Never omit the protocol or use partial paths.

Step 5: Handle the import result

After calling

Unity_ImportExternalModel

Check for success:
- Tool returns
```
success: true
```
  if import succeeded
- Result includes GameObject and Prefab information
- Note the bounds (size and center) for placement
Extract important data:
- GameObject instance ID and name
- Prefab path for reuse
- World size and center (for placement operations)
Report to user:
- Confirm successful import
- Show the GameObject name and prefab path
- Mention the size and position
- Suggest next steps (placement, scaling, etc.)

Step 6: Use with unity-placement skill

After importing, use the bounds information with the

unity-placement

skill for proper positioning:

The imported model has:
- Size: [width, height, depth]
- Center: [x, y, z]
- Prefab: Assets/Prefabs/name.prefab

Consider the size when placing relative to other objects.

Handling user-provided paths

If user provides a partial path

When the user gives an incomplete path, ask for the complete path:

User: "Import models/car.fbx"

Ask for clarification: "I need the complete path to the FBX file. Is it:

A remote URL? (e.g., https://example.com/models/car.fbx)
A local file? Please provide the absolute path (e.g., C:/Projects/models/car.fbx)

What is the full path to car.fbx?"

If user provides a URL without protocol

User: "Import from example.com/models/chair.fbx"

Clarify the protocol: "Should this be:

https://example.com/models/chair.fbx (HTTPS)
http://example.com/models/chair.fbx (HTTP)

Which protocol should I use?"

If user provides a relative path

User: "Import ../models/tree.fbx"

Request absolute path: "Relative paths aren't supported. Please provide the absolute path to tree.fbx.

For example:

Windows: C:/Projects/models/tree.fbx
Mac/Linux: /home/user/projects/models/tree.fbx

What is the full path?"

Best practices

Always verify URL format before calling
```
Unity_ImportExternalModel
```
Never assume paths - always use what's explicitly provided or ask for clarification
Prefer absolute paths over any form of relative path
Include protocol for all remote URLs (http://, https://)
Validate file extension - must be .fbx or .zip
Use simple names - alphanumeric with underscores/hyphens only
Set reasonable heights - 0.1 to 10.0 for most objects
Check import results - verify success and extract bounds data
Coordinate with unity-placement - use bounds for subsequent positioning

Error prevention checklist

Before calling

Unity_ImportExternalModel

, verify:

```
FbxUrl
```
is a complete URL or absolute path
URL includes protocol if remote (http:// or https://)
ALL query parameters are included (everything after ? in the URL)
Path is absolute if local (starts with C:/ or /)
No relative path components (no ../ or ./)
No tilde expansion (no ~/)
Filename ends with .fbx or .zip (query params can follow)
```
Name
```
parameter is a simple identifier (no spaces)
```
Height
```
is a reasonable positive number
```
AlbedoTextureUrl
```
(if provided) is also a full URL/path with all params

Fallback: When Unity_ImportExternalModel is unavailable

Unity_ImportExternalModel

is not available but other Unity MCP tools (like

Unity_RunCommand

) are working, there are two options.

Option A: Enable the tool in Unity

Tell the user:

"The

Unity_ImportExternalModel

tool is not currently enabled. To enable it:

In Unity, go to Project Settings -> AI -> Unity MCP Server
Under the Core section, toggle on
```
Unity_ImportExternalModel
```
The tool will become available immediately — no restart needed."

Option B: Manual import via Unity_RunCommand

If the user cannot or does not want to enable the tool, read

FALLBACK_MANUAL_IMPORT.md

(next to this file) for a step-by-step guide to replicate the import pipeline using

Unity_RunCommand

, based on the reference implementation in the

com.unity.ai.assistant

package.

Quick reference

Required format for FbxUrl

Source Type	Format	Example
Remote HTTPS	`https://domain/path/file.fbx`	`https://cdn.example.com/models/chair.fbx`
Remote HTTP	`http://domain/path/file.fbx`	`http://localhost:8000/model.fbx`
Local Windows	`C:/path/to/file.fbx`	`C:/Users/name/Downloads/robot.fbx`
Local Mac/Linux	`/path/to/file.fbx`	`/home/user/models/tree.fbx`
ZIP archive	Same as above with `.zip`	`https://example.com/pack.zip`

Integration with other skills

With unity-placement

After importing, use the returned bounds with

unity-placement

Imported model "robot_character":
- Size: [0.6, 1.8, 0.4]
- Center: [0, 0.9, 0]
- Prefab: Assets/Prefabs/robot_character.prefab

To place this robot on the platform:
[Use unity-placement skill with the size data]

Remember

The Unity MCP

Unity_ImportExternalModel

tool requires complete, absolute URLs or paths. When in doubt:

Ask the user for the complete path
Verify the URL format before calling the tool
Include the protocol for remote URLs
Use absolute paths for local files
Never guess or auto-complete partial paths
Never use relative paths or tilde expansion

Goal: Prevent import failures by ensuring every

FbxUrl

parameter is a valid, complete, fully-qualified URL or absolute file path.

hz-unity-fbx-import

NPX Install

Tags

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