browser_screenshot

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

With no annotations, the description must disclose behavioral traits itself. It does: 'Expensive and unstructured' warns about cost and output format. It could further note that it captures the current viewport (though the schema covers this via quality options), so a slight gap remains.

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?

Four short sentences, all essential: a warning, the core function, a usage condition, and an alternative directive. Front-loaded with 'LAST RESORT' to prevent misuse. No wasted words.

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 is simple (one optional param, no output schema), and the description covers its purpose, usage constraints, cost, and output format. The qualitative alternatives are explicitly named. This is complete for the tool's 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?

The schema covers the single 'quality' parameter 100% with detailed enum descriptions. The description adds no information about parameters, so 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 clearly states the tool's function: 'Returns a screenshot as base64.' This is a specific verb and resource, and the explicit 'LAST RESORT' framing distinguishes it from sibling tools like browser_debug or browser_query.

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 provides explicit when-to-use guidance ('Only use when the problem is purely visual') and when-not-to-use by naming alternatives ('Always try browser_debug and browser_query first'). This is exactly the kind of exclusionary context needed.

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