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

With no annotations, the description carries full burden. It adds the useful detail that it waits for page load, and specifies the environment. However, it omits failure handling, timeouts, or side effects, which would be expected for a navigation action.

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, efficient sentence that immediately states the action and result. No filler or redundancy.

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 with one parameter and no output schema. The description covers the core behavior but does not mention return values, error conditions, or what happens if the load fails. For a navigation tool with a waiting behavior, this is a noticeable gap.

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 input schema has zero description coverage for the 'url' parameter, and the tool description simply says 'Open a URL' without elaborating on required format, scheme, or other constraints. It adds little beyond the schema's parameter name.

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 action (open URL), the target environment (Safari on iPhone), and an additional behavior (wait for load). This distinguishes it from sibling tools like click, tap, and reload_page.

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?

While no explicit alternatives or exclusions are named, the description clearly implies this is the tool for loading a new URL. The context of sibling tools (reload_page, go_back) makes the use case apparent without further guidance.

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