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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is low, and the description still adds real behavioral detail: result shape (path plus one ordered image, left-to-right then down), the no-match fallback (lists categories), and corpus scale (a few thousand pieces). 'Read-only' is redundant with readOnlyHint but harmless.

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?

Front-loaded with the use condition and tightly packed, with each clause carrying information. It is one long run-on construction with parenthetical asides, which slightly hurts scannability, but nothing is wasted.

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, and the description compensates by explaining the return contents, ordering of the preview image, and the empty-result behavior. Combined with annotation coverage and a fully documented schema, an agent has everything needed to select and call 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 description coverage is 100% and all three parameters carry their own descriptions with examples, so the schema does the heavy lifting. The description reinforces the category fallback behavior but adds no syntax or format meaning for query, limit, or category beyond what the schema already states.

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 specific verb+resource (search the appdesigns library) and enumerates the content domain in concrete terms (SF Symbols, emoji, 3D shapes, glows and blobs, badges, payment and social marks). It also distinguishes itself from siblings by naming create_design and edit_asset as the consumers of the returned path rather than competitors.

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?

Opens with an explicit use condition: 'Use this when a design or a saved asset needs a ready-made piece rather than art you draw.' That cleanly separates it from authoring tools. It does not name a specific alternative tool for the draw-it-yourself case, so it stops short of full when-not/alternatives routing.

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