adb_screenshot

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses the key behavior: returning the screenshot as a base64 PNG. It does not explicitly state that the operation is non-destructive, but taking a screenshot is inherently safe and does not modify the device. This is sufficient for the tool's simplicity.

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 a single sentence that is front-loaded with the action and output format. Every word is necessary and there is no redundancy or fluff.

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?

The tool is simple: one optional parameter, no output schema, no annotations. The description explains what it does and the return format (base64 PNG). This is complete for the tool's complexity; no additional details are needed 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 schema description covers 100% of the parameter (deviceId is described as 'Target device ID (optional)'). The description itself adds no additional information about the parameter, so it provides no extra value beyond the schema. Baseline 3 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?

The description uses a specific verb and resource: 'Take a screenshot of the device screen and return as base64 PNG'. It clearly states the action, the target, and the output format. This distinguishes it from all sibling tools, none of which mention screenshots.

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 implicitly provides clear context: use this tool when you need to capture the device screen. Since no sibling tool performs screenshots, there are no alternatives to exclude. However, it lacks an explicit when-not-to-use statement, though the purpose is so specific that it is not necessary.

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