scroll

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

With no annotations, the description carries the full burden and does well: it discloses the return value (scroll position with atTop/atBottom flags), the container-vs-element distinction, and the lazy-loading repetition pattern. It is thin on failure/timeout behavior beyond what the timeoutMs schema already states, keeping it just under a 5.

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?

A single dense paragraph with the core verb front-loaded and no filler sentences; each clause adds information. It is on the long side and could be broken into a mode list, but nothing is wasted.

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 6-parameter tool with no output schema and no annotations, the description fills the critical gaps by stating the return shape and the lazy-load workflow. It is complete enough to invoke correctly, with only minor omissions around error handling.

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 description coverage is 100%, so the schema already documents all six parameters including the dual role of selector/ref and the deltaY example. The description largely restates this, adding only the 'middle of the screen' target nuance and the container semantics already present in the schema. Baseline 3 is correct.

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?

Opens with a specific verb+resource ('Scroll the page') and enumerates the distinct scroll modes: pixel delta, top/bottom jump, element-into-view, and inside a scrollable container. It further distinguishes itself from sibling tools by noting that click and type already scroll their targets into view.

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?

Gives explicit when-to-use ('reveal content or trigger lazy loading') and when-not-to-use ('click and type already scroll their target into view'). It also prescribes a concrete alternative workflow for infinite scroll, naming the sibling tool wait_for_element and the repeat-until-atBottom condition.

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