Take Screenshot

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

Annotations already declare readOnlyHint and destructiveHint, so the description bears a lower burden. The description adds that the tool returns file path or base64, but does not disclose where the file is saved or whether it blocks until capture is complete. This adds marginal value beyond annotations.

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 extremely concise at 7 words, but may be too terse. It front-loads the action 'Take screenshot' effectively, but could include more information without losing conciseness. There is no unnecessary content, but it sacrifices completeness.

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 the optional parameters and no output schema, the description could be more complete by mentioning that it works on an ADB-connected device and that the file is saved on the device by default. It is minimally adequate but lacks context for an agent to fully understand the tool's operation.

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 input schema has 100% coverage for both parameters, describing them adequately. The description does not add new meaning beyond what the schema provides, such as the default behavior for filename. Baseline score of 3 is appropriate.

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 the tool takes a screenshot and returns either a file path or base64. This provides a specific verb and resource, and no sibling differentiation is needed as there is no other screenshot tool. The purpose is unambiguous.

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 provides no guidance on when to use this tool or how to choose between output formats. While there are no direct siblings to differentiate, the description could mention that it's for capturing the current device screen. It lacks context on prerequisites or typical use cases.

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