browser_screenshot

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

No annotations are provided, so the description carries the full disclosure burden. It does disclose real behavioral facts: viewport is the default mode, images are in CSS pixels, and annotate=true returns a matching snapshot in addition to the image. It is silent on whether the image is returned inline or written to a file, and on any size/rate limits, leaving notable gaps for an unannotated tool.

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?

Three tightly written sentences, front-loaded with the core action and mode enumeration, followed by coordinate interop and annotation behavior. No sentence is redundant and no filler is present.

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?

With no annotations and no output schema, the description does well: it explains capture modes, coordinate semantics, and the annotate return behavior. The remaining gap is the return transport (inline image vs. file path) and any limits on capture size, which an agent would still have to discover.

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 only 67% (fullPage has no schema description), and the description compensates by explaining each parameter's effect: ref selects one element, fullPage selects the whole page, and viewport is the default. It also adds the non-obvious constraint that annotate is viewport-only, which the schema does state but the description reinforces with the return-value behavior.

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 opens with a specific verb+resource ('Screenshot the shared tab') and immediately enumerates the three capture modes: viewport (default), one element, or full page. An agent can distinguish this from siblings like browser_snapshot or browser_evaluate without opening the schema.

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?

It gives a genuinely useful usage rule for the viewport mode (CSS-pixel coordinates work directly with browser_click/browser_hover) and tells when to set annotate=true. However, it never states when to prefer browser_snapshot or browser_evaluate over taking a screenshot, so the choice among visual-capture siblings is left to inference.

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