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

No annotations are provided, so the description carries the full burden. It is a mutation ('Add'), yet it discloses no side effects, no ordering/z-index behavior, no permission requirements, and no indication of what is returned or what happens on failure. The only behavioral hint is the cropping behavior of spriteCoordinate.

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?

Three short sentences, front-loaded with purpose, then parameter guidance. No filler; every sentence earns its place.

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 an 8-parameter tool with a nested object and no output schema, the description is only partially complete. The required screenshotId is undocumented in both the schema and the description, and the coordinate/positioning model lives entirely in the schema, leaving gaps an agent must infer.

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 75%, and the description adds genuine value for the two parameters the schema leaves bare: src (an image URL, sourced from upload_image/list_library) and spriteCoordinate (crops a single pose). It goes beyond the baseline of 3 by explaining the source of src and the intent of the crop object.

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: 'Add an image layer to a card.' An agent can tell this apart from add_text, add_div, and add_platform_set. It does not explicitly distinguish itself from add_screenshot, which is the closest sibling, so it falls short of a 5.

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?

It routes the agent for sourcing src ('such as one from upload_image or list_library') and names the condition for spriteCoordinate ('to crop one pose of a sprite sheet'). However, it never says when to use add_asset versus add_screenshot or generate_asset, so usage is only implied rather than stated.

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