open_url

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It usefully states that the URL opens in Safari or an associated app, but it omits side effects, whether the simulator must already be booted, and how the action interacts with the current session.

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 single front-loaded sentence with no redundant or wasted wording. It efficiently communicates the action and the resulting app context.

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 tool is simple and the schema fully documents both required parameters, with an output schema also present. Still, because there are no annotations, the description should ideally mention prerequisites or behavioral details such as boot state or session requirements.

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 both url and device_id are already documented in the input schema. The description adds no extra parameter semantics beyond what the schema provides, making the baseline score appropriate.

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: 'Open a URL in the simulator.' It also clarifies the likely target environment, Safari or an associated app, which distinguishes it from sibling tools such as launch_app.

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 usage is implied by the action itself: use this when you need to open a URL on the simulator. However, it does not explicitly state when to use this instead of launch_app or other navigation tools, nor does it mention prerequisites such as needing a booted simulator.

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