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

Annotations declare it as a non-read-only, non-destructive, non-idempotent input action, and the description adds genuinely non-obvious context: the coordinates are the touchpad's own 0-1000 space, not screen pixels, with no tap-to-coordinate mapping available. It stops short of describing failure modes or how durationMs affects gesture behavior, so not a full 5.

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 sentences, front-loaded with the action and effect, then coordinate semantics, then routing advice. The em-dash aside about 'no coordinate tapping on a TV' is slightly awkward but carries disambiguating value, so it 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?

For a 7-parameter tool with full schema coverage and no output schema, the description covers purpose, coordinate interpretation, and alternative-tool routing. It omits anything about durationMs behavior or failure handling, but nothing essential for correct invocation 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 the baseline is 3, but the description adds real meaning beyond the schema's bare 'Start X on the touchpad (0-1000)' by clarifying the coordinate space and explicitly warning it is not screen pixels. That disambiguation is exactly the semantic gap the schema leaves open.

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 (swipe), a specific surface (the Apple TV remote's touchpad), and the effect (move focus). It also distinguishes itself from the sibling ios_tv_button by naming it, so an agent can route between them without opening either 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?

Gives an explicit rule: prefer ios_tv_button for single steps, use this tool for longer runs. The alternative is named and the condition selecting each is spelled out, leaving nothing to inference.

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