scroll_by

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

With no annotations provided, the description carries the full behavioral burden. It correctly explains the directionality of positive values, but it does not explicitly state what negative values do (though logically inferable), whether scroll is smooth or instantaneous, or whether it scrolls the main viewport or some focused scrollable container. This is adequate but not rich.

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 sentence that front-loads the operation and directionality with zero filler. Every word adds value, and the key behavioral implication (positive direction) is included without redundancy.

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?

This is a simple two-parameter action with no output schema, so the description plus schema defaults are nearly sufficient. It explains what the action does and how values map to direction, but it could mention that scrolling is relative to the current position and what the default behavior with no parameters is (defaults are already in the schema). For a low-complexity tool, this is complete enough.

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 input schema already documents x and y with 'Horizontal pixels' and 'Vertical pixels' at 100% coverage, so the baseline is 3. The description adds the directional mapping ('positive = down/right'), clarifying that increasing x scrolls right and increasing y scrolls down, which is useful beyond the schema. It does not go into negative-value detail, but the implication is clear.

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 states a specific verb, resource, and mode: 'Scroll the page by a given number of pixels.' The directional convention 'positive = down/right' adds precise semantic clarity. This clearly distinguishes scroll_by from sibling tools like scroll_to_top, scroll_to_bottom, and scroll_to_element, which target absolute positions rather than pixel offsets.

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 phrase 'by a given number of pixels' clearly communicates the use case: when an agent needs precise relative scrolling rather than scrolling to a named position. It does not explicitly mention when not to use it or name alternatives, but the context is strong enough to avoid confusion with the absolute scroll tools among siblings.

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