ios_tap

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

With no annotations at all, the description carries the full behavioral burden. It does disclose the long-press behavior via hold_seconds and its 0-default, which is genuinely useful. But it says nothing about failure modes (stale index, out-of-bounds coordinates), whether the tap requires a booted device, what the action returns, or whether it blocks until the UI settles.

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?

The intent is front-loaded in the first sentence, with parameters following in a scannable Args block. Every line earns its place; the only mild redundancy is restating the parameter names already in the schema keys.

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 five-parameter UI-mutation tool with no annotations and no output schema, the description covers targeting semantics and long-press duration well enough to invoke correctly. What remains missing is precondition and error behavior, which matters for a device-control action but is a smaller gap than the parameter documentation it does provide.

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 0%, yet the Args block documents every one of the five parameters with units ('in points'), the default for hold_seconds ('0 for a normal tap'), the source of index, and the mutual exclusivity of index versus x/y. This fully compensates for the bare 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?

The first sentence states a specific verb (tap) plus two precise targeting modes: an element index from the latest observation, or an (x, y) point in points. An agent can tell this apart from ios_swipe and ios_press by the verb. It stops short of explicitly contrasting itself with the sibling ios_press, but the resource and scope are unambiguous.

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?

Implicit workflow guidance is present: the index parameter is described as coming from 'the latest ios_observe or action result', which tells the agent the observation must precede the tap. However, there is no explicit statement of when to choose index vs coordinates, when to prefer ios_press or ios_swipe instead, or what preconditions (booted simulator, fresh observation) must hold.

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