Scroll

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

Annotations already declare readOnlyHint=true, and the description adds useful behavioral context: it computes a safe swipe in the middle of the screen, avoiding status bar and navigation areas. This goes beyond the annotation without contradicting it. Slight credit for the safety detail, though no additional side effects are disclosed beyond what the read-only hint implies.

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 sentences: first states purpose and key behavior, second gives usage preference. No filler words, every sentence earns its place.

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?

Given the tool's moderate complexity, the description is complete: it covers what the tool does, the safe-swipe behavior, and when to use it. No output schema exists, but for a screen-action tool, return values are not critical. A small gap is that it doesn't explicitly mention the default amount or that direction is required, but these are in the schema.

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 description coverage is 100%, so the schema fully documents parameters (direction enum semantics, amount range, serial default). The description does not add parameter-specific meaning beyond the schema, so baseline 3 is appropriate.

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 description states a specific verb and resource: 'Scroll the screen in a direction.' It also distinguishes from the sibling tool 'swipe' by explicitly recommending this tool over raw swipe for scrolling. This clearly differentiates its purpose.

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?

The description explicitly provides usage guidance: 'Prefer this over raw swipe for scrolling.' This names an alternative tool and specifies when to choose this tool, satisfying the highest bar for this dimension.

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