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

Annotations already declare openWorldHint=true and a non-read-only, non-idempotent, non-destructive profile, but the description adds genuinely new behavioral context: it verifies the resulting URL, never no-ops silently, alters which page is the device's current page, and unlocks pageId-free follow-up calls. This is state-change and side-effect disclosure beyond what annotations provide.

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?

Front-loaded with the core action, then requirements and workflow, so the important content comes first. It is dense and reads as one long paragraph, but each sentence carries actionable information and nothing is pure 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?

Although no output schema exists, the description enumerates the return shape ({ navigated, requestedUrl, finalUrl, pageId, method }), states the post-call state, and lists the sibling tools usable immediately afterward. Nothing an agent needs to call this correctly is missing.

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 coverage is 100% and documents all four parameters, so the baseline is 3, but the description goes further by explaining the pageId defaulting behavior (last landed page, else first loaded page) and why the returned pageId matters. It adds usage meaning rather than restating the schema.

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?

States a specific verb and resource (navigate Safari to a URL on an iOS device) and immediately distinguishes itself from siblings by naming ios_navigate_url as the less-preferred alternative and ios_safari_list_pages as the round trip it avoids. An agent can identify its role without opening any schema.

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?

Gives explicit when-to-use conditions (inspectable page present vs. Safari closed), the prerequisite for the cold-open path (Remote Automation setting), and routing guidance ('Prefer this over ios_navigate_url for Safari'). It also explains when pageId should be omitted versus passed, which is exactly the decision an agent must make.

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