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

With annotations already declaring destructiveHint=true and idempotentHint=true, the description adds useful behavioral context: it specifies the native element-clear command, claims reliability for any field length, describes the focused-field workflow, and notes that an active iOS automation session is required but auto-starts. It does not elaborate on the exact destructive consequences (e.g., whether cleared text is recoverable), but the annotations cover the safety profile.

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 description is a tight paragraph with front-loaded purpose, followed by parameter behavior, a usage pattern, and a session prerequisite. Every sentence adds distinct value and there is 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?

The definition is complete enough for a four-parameter tool with full schema coverage and no output schema: it covers purpose, usage, pattern, and session requirements. It stops short of describing failure modes (e.g., what happens if no field is focused and no label matches), but those gaps are minor given the annotations and 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 already documents all four parameters. The description adds only a small amount of meaning, notably the instruction to tap the field first when omitting `label`; it does not explain `strategy` or `type` beyond what the schema provides.

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 ('Clear a text field on an iOS device') and distinguishes the native element-clear approach from sending backspaces. It also clarifies the two targeting modes (focused field vs. labelled field), making it easy to tell apart from sibling tools like ios_send_keys.

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?

It gives clear context for when to omit `label` (clear the focused field after tapping it) versus when to pass `label` (target a specific field), and provides a usage pattern (tap → ios_clear_text → ios_send_keys). It also contrasts the method with backspacing, but does not explicitly state when not to use this tool or name a direct alternative clear tool.

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