Scroll Browser Page

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

With no annotations, the description carries the full burden. It does disclose that the tool 'Returns the final scroll position' and that it can trigger lazy loading, which is real behavioral value. However, it says nothing about timing (whether it waits for content to load), whether the scroll is instant or animated, or the mode/session implications of an extension vs headless target — notable gaps for a page-mutating 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?

The critical instruction (pixel amount plus sign convention) is front-loaded, and each sentence serves a purpose — direction semantics, concrete call examples, return value, and motivating use cases. The four inline examples are slightly repetitive but cheap and instructive rather than filler.

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?

The description covers purpose, direction semantics, return value, and usage motivation for a 4-parameter tool with a fully documented schema and no output schema. The only shortfall is the absence of guidance on mode/sessionId (extension vs headless), which the schema does describe, so the definition is essentially self-sufficient.

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 baseline is 3, but the description exceeds it by defining sign conventions ('positive y to scroll down, negative y to scroll up') and giving worked examples such as {y: 99999} for bottom and {x: 500} for right. It adds no meaning for the mode or sessionId parameters, which keeps this short of a 5.

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 opening sentence names a specific verb ('Scroll') and resource ('the page') plus the unit of control ('by pixel amount'), which no sibling tool duplicates among the 30+ browser_* tools. An agent can distinguish this from browser_snapshot, browser_navigate, or browser_get_element without opening any 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 gives concrete when-to-use conditions: viewing content below the fold, triggering lazy-loaded images, reaching elements further down the page. It stops short of any when-not guidance or explicit alternatives (e.g., using browser_wait_for or browser_find instead to reach an element), so it is clear context without exclusions.

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