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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds genuinely new operational context: per-minute credit cost and the session ending 3 minutes after the last call. It also discloses return values (URL, title, at_top/at_bottom) that no output schema provides. Minor gap: no statement about behavior when the target element never comes into view.

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 core action and modes in the first clause; the trailing sentence about credits and session expiry is extra but earns its place by preventing surprise costs. Slightly dense, but no dead sentences.

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?

Covers what it does, what changes (lazy-loaded content), what it returns, and session/cost lifecycle — enough to invoke confidently without an output schema. Left unaddressed are edge cases like a never-visible element or scroll limits.

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 all three parameters are already documented, including the 0.8 default and the down default. The description restates those defaults and clarifies that `element` indexes the element list from a prior read, but adds little beyond the schema — baseline 3.

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 (scrolls) and resource (the current page in the user's BookingKoala Cloud Browser) and enumerates the exact modes: by screens, to top/bottom, or until an element is in view. An agent can distinguish this from cotlet_browser_click, navigate, and read 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?

Explains the operative use case — 'content that loads on scroll appears, and the next read lists it' — which tells the agent to scroll before reading rather than instead of reading. It does not explicitly name alternative siblings (e.g., use cotlet_browser_navigate to change pages), so it is a clear-context 4 rather than a routing 5.

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