get_composite_rect

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

With no annotations, the description discloses that it reads visible RGBA from the flattened composite of all layers, and clarifies it reads composited pixels, not a single cel. It does not explicitly state it's read-only but implies no side effects. The return format is mentioned.

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?

The description is well-structured: a title line, a comparison sentence, an Args section with bullet points, and a Returns line. It is relatively concise but includes all necessary information. A slight improvement could be removing 'the rectangular counterpart...' redundancy.

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?

Given no output schema, it explains the return format. It covers input parameters adequately. It does not discuss error handling or performance, but for a read-only tool, it is sufficiently complete.

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 0%, so description must compensate. It lists parameters and provides some context (e.g., 'Top-left x (sprite-global)' for x, y, and default for frame_index). However, it does not explain the coordinate system fully or constraints like maximum region size.

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 it reads visible RGBA over a rectangle from the flattened composite of all layers, and distinguishes itself from the sibling tool get_composite_pixel by noting it reads a rectangular region rather than a single pixel.

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 positions it as the rectangular counterpart of get_composite_pixel, providing clear context for when to use which. However, it does not provide explicit when-not-to-use or alternative tools beyond that one sibling comparison.

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