Screenshot

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the output is a PNG but does not specify whether it captures the full page or just the viewport, whether it waits for page load, or how the image data is returned. This lack of detail leaves significant behavioral ambiguity.

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, concise sentence with no wasted words. It front-loads the action ('Capture') and immediately states the output format and scope, making it easy to parse.

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 parameterless tool, the description covers the core action, but with no output schema or annotations, it should clarify more about the return format or any side effects. The missing details about what happens after capture (e.g., how the PNG is delivered) leave some incompleteness.

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 accepts zero parameters (schema coverage 100% vacuously), so the baseline of 4 applies. The description has no parameter information to add, and no ambiguity exists.

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's function with a specific verb ('Capture'), the resource ('PNG screenshot'), and the scope ('current page'). This distinguishes it from siblings like browser_navigate or browser_click, which have different actions.

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 usage when a visual capture of the current page is needed, but it does not explicitly state when to use this tool over alternatives or provide exclusions. Since no sibling overlaps with this functionality, the context is clear but the guidance is not explicit.

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