take_screenshot

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

With no annotations provided, the description carries the burden of behavioral disclosure. It usefully states that the result is PNG image data, but it does not mention whether the page is modified, what happens when an element selector is invalid, or whether scrolling or waiting is involved. For a capture action this is acceptable but not fully transparent.

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, front-loaded sentence with no filler. It states the action, scope, and output format efficiently, and every part earns 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?

For a simple two-parameter tool with full schema coverage, the description is largely complete: it specifies what is captured and the return type. The absence of an output schema is partially mitigated by mentioning PNG image data, though details like base64 encoding or error behavior are not covered. This is a minor gap given the low complexity.

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 100%, so the parameters are already well documented in the input schema. The description adds only the high-level distinction between viewport and element capture, but no additional parameter-level semantics beyond what the schema provides. Baseline 3 is appropriate.

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 and resource: 'Take a screenshot of the current page viewport or a specific element.' It clearly states the output format ('return PNG image data') and is unambiguous. It also distinguishes itself from the sibling navigation and element-interaction tools by describing a unique capture action.

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 clearly conveys when to use the tool: whenever a screenshot of the visible page or a specific element is needed. It does not explicitly list exclusions or alternatives, but no sibling tool performs screenshots, so additional exclusion guidance is not necessary.

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