ios_open_url

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

Annotations already mark the tool as idempotent and non-destructive. The description adds practical context by noting deep links skip navigation, but it does not disclose potential behavioral side effects such as switching apps or leaving the session context. Given the annotation coverage, this is adequate but not richly transparent.

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 compact sentences with no filler. The first sentence states the operation directly, and the second adds decision-relevant cost guidance. 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?

For a tool with one well-documented parameter, an output schema, and annotations covering safety and idempotence, the description is complete enough. An agent knows what to pass, what the tool does, and when to prefer it over manual UI navigation.

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?

The single parameter is fully documented in the input schema, including type and examples. The description merely restates 'URL or deep link' and does not add new parameter-level meaning. With 100% schema description coverage, the baseline of 3 applies.

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 opens with a concrete verb and resource: 'Open a URL or deep link.' It also positions the tool as the 'cheapest way to reach a screen,' which helps distinguish it from tap-driven navigation tools like ios_tap and ios_launch_app, though it does not explicitly name a sibling alternative.

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 provides a clear heuristic: prefer a deep link to avoid navigating through taps. It explains the benefit of using this tool ('skips the navigation') but does not mention cases where this tool should not be used or name explicit alternatives, so it falls short of a 5.

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