roku_screenshot

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

With no annotations provided, the description carries the transparency burden. It discloses the return behavior (base64 PNG) and implies a prerequisite (the app must be running). It does not explicitly state whether the operation is read-only or what happens if no app is running, but 'screenshot' strongly implies non-destructive behavior.

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, front-loaded sentence communicates the action, scope, and return format without any wasted words. Every clause 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 a zero-parameter tool with an output schema present, the description covers the essential purpose and return format. It is slightly light on failure behavior or explicit side-effect guarantees, but the tool's simplicity and the 'running app' qualifier keep it sufficiently complete for an agent to use it correctly.

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 has zero parameters, so the schema provides no meaningful information. The description does not need to explain parameters; the baseline of 4 applies because there is nothing for it to add. The parenthetical about the return format is more relevant than any parameter detail.

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 uses a specific verb ('Capture') and a clear resource ('screenshot from the running app'), and uniquely distinguishes this tool from all siblings—no other tool in the list captures screenshots. The parenthetical return format removes ambiguity about what the tool produces.

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 implies when to use the tool: whenever a visual screenshot of the currently running Roku app is needed. However, it does not explicitly state when not to use it or point to any alternative, though no direct screenshot alternative exists among siblings.

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