screenshot

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

With no annotations, the description carries the burden and does disclose key behavior: it captures the screen, returns an image, and down-scales to max_width preserving aspect ratio. It also clarifies monitor numbering semantics (0=all, 1=primary, etc.). It doesn't cover permissions, errors, or image format, so it's not a 5.

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 compact and front-loaded with the core action and return value, followed by a neatly formatted Parameters block. Every sentence contributes usage-relevant detail, with 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 two-parameter capture tool without an output schema, this description is nearly complete: it states purpose, return value, parameter semantics, and a helpful reference to list_monitors. The main gap is that it doesn't specify the image return format or error behavior, but that's a minor omission for a simple tool.

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 descriptions are empty (0% coverage), but the description fully documents both parameters: monitor numbering and max_width scaling, including the 0 case to disable. This exceeds the schema's bare type/default information and gives the agent all necessary usage 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?

Description opens with 'Capture a screenshot of the user's screen,' which is a specific verb+resource statement that clearly differentiates it from sibling input/output tools. It also adds the return value purpose: 'so you can see what the user sees.'

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 phrase 'Returns the image so you can see what the user sees' provides a clear use context for visual awareness. It also advises 'Use list_monitors first if you're unsure' for the monitor parameter, giving a practical prerequisite. However, it doesn't mention when not to use or alternative tools.

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