browser_screenshot

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description contributes the viewport-scoping detail ("visible part"), which is useful, but says nothing about the return format (image payload type), whether scrolling is needed to capture more, or whether it works during navigation/loading states.

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?

A single front-loaded sentence with zero filler. The scoping qualifier arrives before the object it modifies, so the key constraint is read first.

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 zero-parameter, read-only capture tool with annotations covering safety, the description is nearly sufficient. The only real gap is that no output schema exists, so the description could have stated what is returned (an image of the viewport) rather than leaving the return shape implicit.

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 takes zero parameters, so per the rubric the baseline is 4. The description correctly implies no configuration is needed, and there is no parameter surface left undocumented.

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 gives a specific verb+resource ("Take a screenshot") and adds a meaningful scope qualifier ("visible part of the current page"), which rules out full-page capture. It does not, however, distinguish itself from the sibling browser_snapshot, which an agent could easily confuse with a visual capture tool.

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?

Usage is only implied: an agent can infer this is the tool to reach for when it needs a visual rendering rather than page structure. There is no explicit when-to-use statement, no mention of browser_snapshot as the text/DOM alternative, and no note about prerequisites such as a page being loaded or navigation state.

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