Take a screenshot

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

Annotations already provide readOnlyHint=true and destructiveHint=false, and the description adds the important behavioral trait that 'Screenshots cost a lot of context,' which is not in the annotations. This is valuable additional context about resource consumption, though it doesn't detail output format or other behaviors beyond that.

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 two concise sentences with zero filler. It front-loads the core purpose and then immediately provides usage guidance, making every word earn its place.

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?

The description is complete for a screenshot tool. It covers when to use it, and the schema fully documents all parameters including default behaviors like viewport capture and file saving. No critical information is missing for an agent to call it correctly.

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 input schema has 100% coverage with detailed descriptions for all 7 parameters, so the description does not need to add parameter-level meaning. The description adds nothing beyond the schema, so it meets the baseline for high schema coverage.

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 states the exact action 'Capture the page as an image' with a clear verb and resource, and it distinguishes itself from the sibling browser_snapshot by mentioning the alternative. This makes the tool's purpose unambiguous and sets it apart from related tools.

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 explicitly advises 'prefer browser_snapshot, and use this only when you need to see pixels,' which clearly states when to use this tool versus the alternative. This is direct and actionable usage guidance.

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