read_pixels

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

With no annotations, the description carries the full burden; it does disclose meaningful behavior — output is a character grid with a legend, transparency renders as '.', output is flattened unless a layer is named, and a region can be cropped. It says nothing about failure modes, permissions, or how large a grid can get, which matters for a pixel dump.

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?

It is short and front-loads the return format, but the phrasing is telegraphic fragments ('Flattened unless layer. Optional region.') that force the reader to reconstruct the meaning. Nothing is wasted, yet the compression costs parseability.

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 7-parameter tool with no annotations, no output schema, and only 29% schema coverage, the description is too thin: path and frame are unexplained and the region parameters are only hinted at. It covers the return shape but not enough of the call contract.

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 only 29%, so the description must compensate; it does explain layer (default flattening) and gestures at x/y/width/height via 'region'. Path, frame, and the exact region semantics remain undocumented in both the schema and the description, so the compensation is partial.

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 concrete verb+resource: it reads pixels and returns them as a char grid plus legend, and it specifies the encoding (draw rows format, '.'=transparent). It does not distinguish itself from adjacent siblings like preview or export, which likely also produce a view of the sprite, so an agent can't fully rule out alternatives from the description alone.

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?

'Flattened unless layer' and 'Optional region' implicitly tell the agent when to pass layer or a region, but there is no explicit when-to-use/when-not framing and no named alternative (preview, export) is offered. Usage must be inferred.

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