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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful context: the link is viewable without sign-in, pricing is only an estimate, and the buyer finalizes total and payment in Checkout — clarifying that this tool does not transact. It omits things like link lifetime/expiry, whether repeated calls with the same IDs return the same URL, and what exactly is returned.

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?

Two tight sentences, zero redundancy, and the functional statement is front-loaded ahead of the checkout clarification. Nothing could be removed without losing 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?

For a single-parameter, annotation-covered, non-destructive tool, the description covers the key ambiguity agents would have — that this is a shareable estimate, not a checkout. Remaining gaps (return value shape, link expiry, duplicate handling) are minor but real given there is no output schema.

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 schema encodes real constraints (1-26 items, ID pattern ^[a-z][a-z0-9-]{0,47}$), but schema description coverage is 0%, so the only signal is the bare 'productIds' name. The description says 'selected mods' but adds nothing about ID format, ordering, duplicates, or the 26-item cap, so it does not compensate for the coverage gap.

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 ('Prepare a public cart link with selected mods'), which is enough for an agent to distinguish it from the read-only lookup siblings (search_catalog, get_mod_details, get_compatibility_guidance). It stops short of naming a sibling or contrasting scope, so it is clear but not maximally differentiated.

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?

Usage is implied rather than stated: the agent can infer this is the step after selecting mods, and that it does not complete a purchase. There is no explicit when-to-use/when-not-to-use guidance relative to the sibling tools, and no stated prerequisites such as requiring valid catalog product IDs.

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