Find responsive breakpoints (width sweep)

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

With no annotations provided, the description carries the full burden, and it does well: it discloses that the tool mutates the viewport, probes overflow, and 'restores the prior viewport afterwards.' It also clarifies it is image-free, which avoids expectations of screenshots. It does not mention wait/load behavior or exact reporting format, but core side effects are covered.

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, tightly written, with the core behavior front-loaded and no filler. The phrase about the four named viewports earns its place by explaining why this tool exists despite other responsive audits.

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 tool with no output schema, the description sufficiently states what is returned ('exact width ranges where the layout breaks') and covers side effects. It could be more explicit about output format or load-wait behavior, but the definition is complete enough for correct invocation.

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 coverage is 100%, so the schema already documents every parameter. The description adds algorithmic context by mapping minWidth/maxWidth and step to the width sweep, but it does not add per-parameter meaning beyond the schema. 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 names a specific verb and resource: it stress-tests responsive layout by sweeping viewport width and reporting breakpoint ranges. It is clearly distinguished from the sibling viewport audits by its zero-image, incremental width-sweep approach and by contrasting with the 'four named viewports'.

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 conveys clear context: use this when you need to find width ranges where horizontal overflow occurs, especially ones 'the four named viewports skip over.' It does not explicitly name alternatives or give when-not-to-use rules, so it stops short of a 5.

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