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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered; the description adds real value beyond that by disclosing the fallback path (document.cookie, non-httpOnly only) when the CDP call is unavailable and the auto-pick behavior for the active page. This warns the agent that results may be incomplete, which is meaningful behavioral context.

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?

Three sentences, front-loaded with the primary action and resource, then mechanism, fallback and the one parameter caveat. No filler; every clause carries information.

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?

With no output schema, the description usefully enumerates the returned fields (httpOnly/secure/sameSite/domain/path/expiry) and the fallback degradation, which is enough for an agent to interpret results. Minor gaps (e.g. no explicit note on missing-cookie or empty-result behavior) keep it just under complete.

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 the baseline is 3; the schema already documents udid, pageId and the ignored platformVersion in detail. The description's pageId note restates the schema's own wording rather than adding syntax or constraints beyond it.

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?

Specific verb (Get) plus resource (cookies) scoped to a Safari page on an iOS device, with the underlying mechanism (Web Inspector / Page.getCookies) named. An agent can distinguish it from siblings like ios_safari_evaluate or webpage_clear_cookies without opening a 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 a clear use context ('useful for debugging auth/session state') and direct parameter guidance ('Omit pageId to auto-pick the active Safari page'). It does not, however, explicitly name an alternative tool or state when-not-to-use (e.g. reach for ios_safari_evaluate for arbitrary JS), so it stops short of full routing guidance.

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