Screenshot

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

No annotations are provided, so the description bears the full burden. It states the action (capture) and format (PNG) but omits crucial details: whether it modifies state, if a browser window must be open, what exactly 'current browser window' captures (viewport vs full page), and if there are side effects.

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 9-word sentence, efficient and front-loaded. However, it could include additional essential context (e.g., 'captures the visible viewport area') without losing conciseness, making it slightly under-specified.

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?

Given zero parameters and no output schema, the description should clarify what the tool returns (e.g., base64 PNG data). It only says 'as a PNG image' but doesn't confirm the output type. The scope of 'current browser window' is ambiguous, and prerequisites are missing, leaving the agent uncertain.

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?

There are zero parameters, and the schema coverage is 100% (trivially). The description adds minimal meaning by specifying 'current browser window' as the implicit input. A baseline of 4 is appropriate given no parameters to document.

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 resource ('current browser window') with a clear output format ('PNG image'). It is distinct from sibling tools like 'navigate' or 'inspect_page' which serve different purposes.

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 screenshot versus alternatives. Despite having sibling tools (e.g., inspect_page, wait_for), no exclusions or context is given. An agent must infer use case from tool purpose alone.

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