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

Goes well beyond the readOnly/idempotent/openWorld annotations: it says the motion emulates a human mouse wheel, that lazy content becomes visible only after scrolling, that the response includes URL, title, and at_top/at_bottom, and that every started minute bills credits with the session expiring 3 minutes after the last call. That is material operational context an agent cannot get from the annotations.

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?

Three tight sentences: behavior and modes first, then the lazy-load payoff, then return value and cost model. No filler, and the most decision-relevant information is front-loaded.

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?

There is no output schema, yet the description names the returned fields (URL, title, at_top/at_bottom) and covers the credit/session lifecycle. Combined with the fully documented 3-parameter schema and the annotations, an agent has everything needed to call this correctly.

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% and the schema already documents element, screens (with the 0.8 default and 10 cap), and direction. The description mostly restates those in prose, though it does sketch how the modes relate (screens applies to down/up, element overrides distance). Baseline 3 is appropriate since the schema does the heavy lifting.

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 Substack Cloud Browser) and enumerates the exact modes: down/up by `screens`, to top/bottom, or until an element is in view. That vocabulary separates it cleanly from cotlet_browser_read, cotlet_browser_click, and cotlet_browser_navigate 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?

"Content that loads on scroll appears, and the next read lists it" gives a clear when-to-use signal: call this to trigger lazy loading before a read. It does not explicitly exclude or contrast the other browsing siblings (navigate, click, read) or say when scrolling is unnecessary, so it falls short of a full when/when-not/alternatives statement.

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