Scroll

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

No annotations are provided, so the description carries the full burden. It never states how far the scroll moves, whether the scroll animates/settles, whether it fails or no-ops at the end of content, or what the tool returns. Only the direction semantics ("down" shows what is below) is disclosed.

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?

Two short sentences, front-loaded with the action and its purpose, with the optional-element case trailing. 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 3-parameter interaction tool with no annotations and no output schema, the description omits the scroll distance, whether the screen state is returned or must be inspected via phone_look, and failure behavior at the end of content — all things an agent needs to drive this reliably.

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?

At 67% schema coverage, the schema documents ref ("scrollable element ... Default: the whole screen") and serial. The description only adds meaning for direction by glossing "down" as showing what is below; it says nothing about ref or serial beyond the schema.

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?

"Scroll to reveal more content in a direction" is a specific verb+resource with the effect of the action stated. It does not, however, distinguish itself from the sibling phone_swipe (also a directional gesture) — the only edge is that scroll is content-revealing and swipe is generic, and that is left implicit.

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?

"Scroll to reveal more content" implies usage, and "Optionally inside a scrollable element" hints at when to pass ref. But there is no explicit when-to-use vs phone_swipe, no note on pairing with phone_look to verify what appeared, and no exclusions.

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