Capture a tiled screenshot of a web page

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

Annotations already indicate read-only and open-world behavior, so the bar for adding value is lowered. The description goes beyond annotations by detailing built-in robots.txt compliance, rate limiting, caching, and the return format (tiled PNG screenshots). These specifics help the agent anticipate external interactions and constraints, though it doesn't mention failure modes or auth needs.

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 three concise sentences. The first sentence front-loads the purpose ('For explicit visual inspection'), the second explains the mechanism, and the third lists key behavioral features. Every word earns its place, with 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?

Despite having no output schema, the description explicitly states the return format ('tiled PNG screenshots'). It also covers web-access constraints (robots.txt compliance, rate limiting) and caching behavior. Combined with the comprehensively described parameters and informative annotations, the description provides a complete picture for an agent to select and invoke the tool 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 provides complete descriptions for all four parameters (100% coverage), so the baseline is 3. The description itself does not add parameter-level detail, but it does mention 'tiled' which indirectly relates to the width and fullPage parameters. However, since the schema already explains each parameter sufficiently, the description offers no additional semantic value beyond the schema.

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 clearly states the tool's function with a specific verb and resource: 'Renders the page with a headless browser and returns tiled PNG screenshots.' It also frames it as 'For explicit visual inspection,' distinguishing it from sibling tools like fetch and links that handle content extraction. The purpose is unambiguous and differentiated.

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 opening phrase 'For explicit visual inspection' provides clear context on when to use the tool. However, it does not explicitly name alternatives or discuss when not to use it, only implying that other tools are better for non-visual tasks. Lacking explicit exclusions, it stops one step short of a perfect score.

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