Render a node to an image

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

Beyond the annotations (readOnlyHint false, etc.), the description discloses key behaviors: best-effort rendering with approximation/unsupported flags, fallback to SVG text when the rasterizer is missing, automatic scale lowering to respect maxSize, refusal of subtrees over maxNodes, and directory creation with savePath. These are not captured by structured annotations.

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 dense paragraph is front-loaded with the core purpose, then limitations, then defaults and parameter-specific nuances. Every sentence adds operational value without redundancy, and the structure is easy to scan.

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?

For a tool with 8 parameters and no output schema, this description covers all parameters' defaults, constraints, fallbacks, and output modality (inline vs saved file). It also explains the report's role (approximated/unsupported) and points to alternative tools for exact values, giving an agent everything needed to invoke it correctly.

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 100%, but the description adds deep meaning: defaults for scale (2), maxSize (1568), and background (transparent); the condition for savePath (required when PNG > 2097152 bytes or SVG > 50000 chars); and the behavior that a page guid downscales to fit maxSize. This goes well beyond the schema's per-parameter descriptions.

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?

The description clearly states a specific verb ('Render') and resource ('a node') with explicit node types (frame, component, instance, group, shape, text, or whole page) and output formats (PNG or SVG). It also distinguishes from siblings by noting the offline nature and that this is for visual inspection.

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?

The description explicitly says 'Rendering is best-effort: read `approximated` and `unsupported` in the report before trusting fine details; exact values remain available from fig_node / fig_style / fig_text.' This names alternative tools and the exact condition under which to prefer them. It also clarifies when to use savePath (when output exceeds size limits) versus inline return.

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