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pictify_create_canvas_image

Generate images from FabricJS canvas JSON data with variable substitution. Render canvas designs directly without saving as templates first.

Instructions

Generate an image from FabricJS canvas JSON data with optional variable substitution. Use this when you have a FabricJS canvas design (created in the Pictify visual editor or programmatically). Templates in Pictify are built using FabricJS — this endpoint lets you render canvas JSON directly without saving it as a template first. For rendering a saved template, use pictify_render_template instead. Returns the hosted image URL (CDN-backed).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
fabricJSDataYesFabricJS canvas JSON object. This is the serialized canvas data from FabricJS (canvas.toJSON()). Contains objects array with shapes, text, images, and their properties.
variablesNoVariables to substitute into the canvas elements that have variable bindings.
variableDefinitionsNoVariable definitions describing the types and defaults for each variable.
widthNoOutput image width in pixels. If omitted, uses the canvas width.
heightNoOutput image height in pixels. If omitted, uses the canvas height.
fileExtensionNoOutput image formatpng

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

A4.4/5.0
Behavior3/5

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

No annotations provided, so description carries full burden. Discloses return value ('hosted image URL, CDN-backed') but lacks details on auth requirements, rate limits, or side effects. Does not explicitly state read-only or destructive nature, though 'generate' implies non-destructive.

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?

Four sentences, front-loaded with purpose and usage guidelines. Every sentence adds value, no redundancy or wasted words.

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

Completeness4/5

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

Covers the core functionality, return value, and distinction from sibling tool. Could mention potential limitations or error conditions, but given the complexity and no output schema, it's fairly complete.

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?

All 6 parameters have schema descriptions (100% coverage), and the description adds meaningful context beyond the schema, e.g., explaining variable substitution and FabricJS JSON structure. Provides a brief overview of what variables and fabricJSData are.

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?

Clearly states 'Generate an image from FabricJS canvas JSON data with optional variable substitution', specifying the verb (generate), resource (image from JSON), and feature (variable substitution). Explicitly distinguishes from sibling tool pictify_render_template by stating when to use each.

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

Usage Guidelines5/5

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

Provides precise guidance: 'Use this when you have a FabricJS canvas design...' and 'For rendering a saved template, use pictify_render_template instead'. Also notes that it renders directly without saving as template first.

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