screenshot

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

The description discloses that the tool saves a PNG file to a specific directory and returns the path. Annotations already mark it as readOnlyHint: true, and the description adds behavioral context beyond that, such as file location and naming convention.

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?

Two sentences with no extraneous information. The first sentence states the main action and parameter option; the second provides output details. Front-loaded and efficient.

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 simple screenshot tool with no output schema, the description covers the action, parameter behavior, output format, and return value. No additional information is needed for 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?

Schema coverage is 100% with parameter descriptions. The tool description adds value by explaining the behavior of active_window parameter (capture focused window) and the default path behavior, going beyond the schema.

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 captures a screenshot, either full screen or active window, and specifies the output format and location. It distinguishes itself from sibling tools which are unrelated to 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 explicitly explains the two modes (full screen vs active window) via the active_window parameter, which serves as guidance. Since no alternative screenshot tool exists, explicit alternatives are unnecessary.

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