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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the bar is lower; the description still adds real context by naming the returned metadata fields, flagging that thumbnails are large base64 payloads and off by default, and noting extra catalog fields present only on marketplace clones. It does not disclose ordering, rate limits, or behavior when a project_id matches nothing.

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 purpose, then filters, then return shape, then cross-tool hints in four dense sentences with no filler. Each sentence carries distinct information an agent would otherwise have to infer.

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 enumerating the returned metadata fields and the conditional marketplace-only fields. Small gaps remain around result ordering and what an empty result looks like, but nothing essential to calling the tool correctly is missing.

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%, so all five parameters are already documented in the schema; the description largely restates project_id, marketplace_asset_id, search, and include_thumbnails. It adds marginal value by naming the provenance of marketplace_asset_id (from list_marketplace_assets / get_marketplace_asset) and framing width/height as the source for generate_pixel_art.size. Baseline 3 applies when the schema does the heavy lifting.

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 and resource scoped to the signed-in user's pixel art assets, and immediately distinguishes itself from get_asset ('call get_asset to fetch PNGs') and from marketplace listing tools via the marketplace_asset_id filter. An agent can identify what this returns without opening the schema.

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?

Gives clear routing: use include_thumbnails=false plus get_asset for images, and reuse width/height as generate_pixel_art.size when extending a set. It also warns that multi-artboard documents surface individual artboards via get_asset rather than as packed spritesheets. It lacks an explicit 'do not use this when...' exclusion and says nothing about ordering or pagination beyond the limit parameter.

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