open_url

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

With no annotations provided, the description carries the burden of behavioral disclosure. It discloses that on iOS it uses Appium/WDA and defaults to a configured browser bundle id, which adds transparency. It does not mention all behaviors (e.g., Android handling or if it waits for page load), but for a simple open-URL tool, it provides meaningful context beyond a bare statement.

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 two sentences, front-loaded with the core action, and adds a concise platform-specific note. Every sentence earns its place with no wasted words.

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?

Given the tool's simplicity, the description covers the main context: what it does, iOS-specific behavior, and default bundle id. The presence of an output schema reduces the need to explain return values. It lacks Android specifics, but overall it is reasonably complete for this action.

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 0%, so the description must compensate for explaining parameters. It only indirectly references bundle_id ('defaults to the configured browser bundle id') and gives no explicit meaning for device or url. The url property is somewhat obvious from the tool name, but device and bundle_id remain under-explained, leaving the agent to infer or guess.

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 clearly states the tool's function: 'Open a URL in the platform browser.' It uses a specific verb ('Open') and resource ('URL'), and adds platform context. This distinguishes it from sibling tools like launch_app or web_search, which have different purposes.

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 clear context for when to use the tool: to open a URL in the browser. It also gives platform-specific details (iOS uses Appium/WDA, default bundle id). However, it does not explicitly mention alternatives or when not to use it, so it falls short of a full 5.

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