preview_display

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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description adds the meaningful detail that the result is a rendered-canvas snapshot rather than a hardware camera image. It does not mention image format, resolution, or whether the canvas reflects pending draws, which would be a nice addition but is not critical.

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?

A single semicolon-joined sentence with the primary action front-loaded and the disambiguation second — no filler.

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 zero-parameter, read-only tool with no output schema, the description adequately conveys what comes back (an image of the rendered canvas) and what does not (a camera view). Minor gaps remain around image format/size, but nothing blocks correct invocation.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline of 4 applies.

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 ('return the current rendered canvas as an image') and immediately distinguishes itself from the camera-oriented siblings (record_camera, capture_camera) with 'not a camera view of the LCD'.

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 exclusion clause tells the agent when not to use this tool (i.e. when a physical camera capture is wanted), which implicitly routes to the camera tools. It lacks an explicit positive 'use when you want to see what is currently on the display' framing, but the context is clear.

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