Capture hidden interactive UI

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

Annotations indicate non-read-only, non-idempotent, non-destructive, open-world behavior. The description adds that the tool 'operate[s] interactive triggers' and captures screenshots, providing useful behavioral context beyond the annotations. It doesn't disclose potential side effects like form submissions, but the openWorldHint covers general live-site interaction.

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?

Two sentences, front-loaded with the primary action and supported by concrete examples of trigger types and outputs. Every sentence earns its place, with no fluff or repetition of schema information.

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 the tool's complexity (13 parameters, output schema exists), the description provides a sufficient high-level overview: what it finds, how it operates, and what it captures. The output schema covers return details, so the description does not need to explain them. Minor gap: it doesn't mention the need for a real browser or network access, but that's not essential.

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 has 100% coverage with detailed descriptions for all 13 parameters, so the baseline is 3. The description does not add parameter-specific details beyond what the schema provides, but that is acceptable given the high schema coverage.

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 ('operate') and resource ('interactive triggers') and clearly distinguishes itself from siblings by stating it 'surfaces the parts of a design that never appear in a static extraction,' which differentiates it from static capture tools like capture_screenshot.

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 implies when to use it: when hidden interactive UI needs to be revealed, contrasting with static extraction. It does not explicitly exclude alternatives or name sibling tools, but the context is clear enough for an agent to infer the appropriate scenario.

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