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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description's 'Read-only' is redundant; however 'Anonymous — no sign-in required' adds real auth context the annotations do not capture, which matters in a suite where auth_status and logout exist as siblings.

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?

A single compact sentence with the resource and contents front-loaded, followed by two short qualifiers for auth and safety. No filler, and each clause carries distinct 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?

Return shape is covered by the output schema and the description reinforces it; auth is stated and the safety profile is covered. For a zero-parameter read tool this is essentially complete, with only the absence of a named alternative keeping it from a 5.

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 tool takes zero parameters, so the baseline of 4 applies and there is no parameter semantics to compensate for. The enumerated field list mirrors what the output schema already defines, adding mild but non-harmful reinforcement.

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 ('Show') and resource ('current shopping cart') and enumerates the returned contents (items, options, quantities, line prices, subtotal), which distinguishes it from siblings like get_order_history or review_order that deal with placed orders. An agent can select it without opening the 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?

Qualifying it as 'current' plus 'Anonymous — no sign-in required' implies the natural use case (pre-checkout cart inspection) and clears a common precondition, but there is no explicit when-not guidance or named alternative such as review_order for a finalized cart.

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