Scroll

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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, which only imply the view state changes), the description adds genuinely useful behavior: the response shows the new view, already-pinned regions are named rather than re-emitted, and at-boundary conditions are reported. It does not describe whether the returned view is a full snapshot or a diff, which is the one remaining behavioral unknown.

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 compact sentences with the primary behavior front-loaded and the ref variant immediately after; every clause (default amount, pinned-element handling, boundary reporting) carries distinct 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?

With no output schema, the description does a solid job covering what a scroll returns (new view, named sticky elements, top/bottom notice). The only gap is not stating whether the new view is a full snapshot payload versus a partial diff, which matters for a browser tool.

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 ref, screens, and direction are already fully documented in the schema; the description only restates the 'one screen down by default' and ref behaviors. Correct baseline for a tool whose parameters are covered by structured data, with no added format or interaction detail.

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?

Specific verb ('scroll') plus resource ('the current tab') with the default unit of movement stated, and it explicitly distinguishes the two modes (plain scroll vs. ref-based element scroll). An agent can separate this from browser_snapshot or browser_navigate without opening the schema.

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 clearly says when the ref path applies ('with ref, scroll that element into view instead') and that plain scrolling is one screen down by default, which is enough to choose a mode. It does not name a sibling alternative (e.g., when to prefer browser_snapshot over scrolling to inspect content), so it falls short of the explicit when-not guidance a 5 requires.

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