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

Since no annotations are provided, the description carries the full burden. It clearly discloses the limitation of only affecting non-HttpOnly cookies, the use of document.cookie, the lack of verification after clearing, and the return format. It does not, however, discuss potential failure scenarios, permissions needed, or whether the operation is idempotent. Still, for a simple tool the disclosure is adequate.

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 three sentences long, no wasted words. The first sentence immediately conveys the core purpose. The second sentence provides the alternative recommendation concisely. The third sentence describes the return value and a key behavioral note. Every sentence earns its place.

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 is complete. It covers the tool's scope, limitations, the recommended alternative, the return value, and the lack of verification. Even without an output schema, the return type is described. No crucial information appears to be missing for a developer to use this tool correctly.

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% (all 4 parameters have descriptions). The tool description adds one piece of information not in the schema: that 'pageId' is auto-picked when omitted. Otherwise, the description does not elaborate on parameter semantics beyond what the schema already provides. With high coverage, the baseline is 3, and the added value is minimal.

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 uses a specific verb ('expire') and clearly identifies the resource ('NON-HttpOnly cookies'), the scope ('visible to current page origin'), the method ('document.cookie'), and the platforms ('iOS Safari or Android Chrome'). It also distinguishes itself from the sibling tool 'webpage_clear_browsing_data' by explicitly stating its limitation regarding HttpOnly cookies.

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 explicit guidance on when to prefer the alternative tool 'webpage_clear_browsing_data' and why that tool is generally better (reaches HttpOnly cookies, verifies results, clears additional storage). It then clarifies that this tool exists for callers who specifically need the 'document.cookie' behavior, making the usage context very clear.

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