browser_scroll

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

Annotations declare idempotency and non-destructiveness, but the description goes well beyond them: it discloses the return token ('scrolled'), the prerequisite (browser preview open with agent access), the concrete failure mode and timing (~6 s, 'no preview pane running'), and an auth gate on credential-bearing pages. Rich behavioral context that annotations do not carry.

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?

Front-loaded with the verb and resource, then the mechanism, then alternatives, then prerequisites and failure behavior. Dense but every clause earns its place; no 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?

For a two-parameter scroll tool with no output schema, the description covers the action, return value, prerequisites, failure timing, and access restrictions. Nothing needed to invoke it correctly is missing.

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 both x and y are already fully documented with units, defaults, and minimums. The description only reinforces that the position is absolute rather than relative, adding marginal value over the schema. Baseline 3 applies.

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?

States a specific verb+resource (scroll the preview's window), names the underlying mechanism (window.scrollTo), and specifies absolute positioning. It is immediately distinguishable from browser_click, browser_frame, and browser_eval, all of which it references.

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?

Explicitly routes the agent: use this before browser_frame, browser_click already scrolls its own target, and a nested scroll container requires browser_eval. This is exactly the when-to-use/when-not-to-use guidance that selects among siblings.

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