Take Screenshot

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

With no annotations, the description must disclose behavioral traits. It only states the action and coordinate reference, but omits whether the operation is read-only, what the return format is, or any side effects. The phrase 'CSS viewport pixel coordinates' adds some precision but insufficient transparency for a tool with no other behavioral metadata.

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 sentence that is efficiently worded and front-loaded with the core action. Every word adds value; there is no redundancy or 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?

The tool has two parameters, no output schema, and no annotations, but the description does not explain the return value, parameter behavior, or usage context. It is too sparse to fully support an agent in selecting and invoking the tool correctly, especially without schema-level descriptions.

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 description coverage is 0%, so the description must compensate by explaining parameters. However, it never mentions 'overlay' or 'crosshair' or how they relate to the capture. The description fails to add meaning beyond the raw schema, leaving the agent without semantic understanding of the parameters.

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 uses a specific verb ('Capture') and identifies the resource ('selected tab viewport') with a technical detail ('using CSS viewport pixel coordinates'). It clearly distinguishes the action from sibling tools like click or scroll, leaving no ambiguity about what the tool does.

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 provides no guidance on when to use this tool or how it compares to alternatives. There is no mention of scenarios like visual verification or when a screenshot is preferred over other operations, so the agent receives no usage context.

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