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get_viewport_screenshot

Capture screenshots of the Blender 3D viewport to document scenes, share progress, or create reference images for AI-assisted modeling workflows.

Instructions

Capture a screenshot of the current Blender 3D viewport.

Parameters:

  • max_size: Maximum size in pixels for the largest dimension (default: 800)

Returns the screenshot as an Image.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
max_sizeNo

Implementation Reference

  • The main handler function for the 'get_viewport_screenshot' MCP tool. It uses a persistent socket connection to Blender to request a viewport screenshot, saves it temporarily as PNG, reads the bytes, cleans up, and returns an MCP Image object. The input schema is defined by type hints: max_size (optional int, default 800).
    @mcp.tool()
    def get_viewport_screenshot(ctx: Context, max_size: int = 800) -> Image:
        """
        Capture a screenshot of the current Blender 3D viewport.
        
        Parameters:
        - max_size: Maximum size in pixels for the largest dimension (default: 800)
        
        Returns the screenshot as an Image.
        """
        try:
            blender = get_blender_connection()
            
            # Create temp file path
            temp_dir = tempfile.gettempdir()
            temp_path = os.path.join(temp_dir, f"blender_screenshot_{os.getpid()}.png")
            
            result = blender.send_command("get_viewport_screenshot", {
                "max_size": max_size,
                "filepath": temp_path,
                "format": "png"
            })
            
            if "error" in result:
                raise Exception(result["error"])
            
            if not os.path.exists(temp_path):
                raise Exception("Screenshot file was not created")
            
            # Read the file
            with open(temp_path, 'rb') as f:
                image_bytes = f.read()
            
            # Delete the temp file
            os.remove(temp_path)
            
            return Image(data=image_bytes, format="png")
            
        except Exception as e:
            logger.error(f"Error capturing screenshot: {str(e)}")
            raise Exception(f"Screenshot failed: {str(e)}")
Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool captures a screenshot and returns it as an Image, but lacks critical details such as whether this operation is read-only or has side effects, permission requirements, performance impact, error conditions, or format specifics (e.g., PNG, JPEG). The description is minimal and misses key behavioral traits.

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

Conciseness5/5

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

The description is highly concise and well-structured: a clear purpose statement followed by a bullet point for parameters and a note on returns. Every sentence earns its place with no wasted words, and key information is front-loaded effectively.

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

Completeness2/5

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

Given the tool's moderate complexity (capturing a screenshot in a 3D application), no annotations, no output schema, and low schema coverage, the description is incomplete. It lacks details on behavioral aspects like side effects, error handling, and output format specifics, leaving gaps for an AI agent to understand full usage context.

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

Parameters4/5

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

The description adds meaningful context for the single parameter 'max_size' by explaining it's the 'Maximum size in pixels for the largest dimension' with a default of 800, which goes beyond the schema's basic title and type. With 0% schema description coverage and only one parameter, this compensates adequately, though it could specify units or constraints more explicitly.

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

Purpose5/5

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

The description clearly states the specific action ('Capture a screenshot') and target resource ('current Blender 3D viewport'), distinguishing it from all sibling tools which involve downloading assets, executing code, getting statuses, or modifying scenes. The verb+resource combination is precise and unambiguous.

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

Usage Guidelines3/5

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

The description implies usage when a screenshot of the Blender viewport is needed, but provides no explicit guidance on when to use this tool versus alternatives (e.g., other screenshot methods or tools for different outputs). There's no mention of prerequisites, limitations, or comparisons with sibling 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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