Simulate a touch on an iOS simulator element by index, predicate, or coordinates to automate UI interactions and verify app behavior.
Tap an element by index (from UI tree), predicate, or coordinates.
| Name | Required | Description | Default |
|---|---|---|---|
| x | No | X coordinate | |
| y | No | Y coordinate | |
| index | No | Element index from UI tree | |
| device_id | Yes | Simulator UDID | |
| predicate | No | Element predicate |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It says nothing about whether the tap blocks until completion, what happens on a missing element, whether coordinates are in device or screen space, or what the return value is. For a UI-interaction mutation, this is a significant gap.
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?
A single front-loaded sentence with no waste. Slightly terse given the three targeting modes that could warrant a clarifying clause.
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?
An output schema exists, so return values need not be explained. However, with no annotations for a mutating interaction tool and no guidance on mode selection or failure behavior, the description is only minimally complete.
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 all five parameters are already documented. The description adds only that index comes 'from UI tree' and predicate identifies an element, which is marginal beyond the schema. Baseline 3 is correct.
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 ('Tap') and resource ('an element'), and enumerates the three targeting modes (index, predicate, coordinates). This distinguishes it from siblings like double_tap and long_press.
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 three modes imply when each applies (index from UI tree, predicate match, raw coordinates), but there is no explicit guidance on which to prefer, no prerequisites, and no exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.