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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: it clarifies that no order is created, no charge occurs, no terms are accepted, and no paid files are provided. It also notes that the price is before tax, which is useful for the agent to communicate to the buyer. This goes beyond the annotations without contradicting them.

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, each earning its place: the first states the core function, the second clarifies non-behaviors, and the third adds a pricing caveat. It is front-loaded with the main purpose and avoids redundancy with the schema or annotations.

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 simple read-only link-return tool with one parameter and no output schema, the description covers the essential context: what the link is for, what it does not do, and a pricing caveat. It does not describe the return format (e.g., whether the link is a string or object), but with no output schema and a simple use case, this is a minor gap. The description is complete enough for an agent to call the 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 0%, so the description must compensate for the single parameter productId. The description does not explicitly explain what productId is or how to format it, but the schema provides a pattern and length constraints. The description's mention of 'product-page link' implies productId identifies the product, but it doesn't add much semantic meaning beyond the schema. With only one parameter and a clear schema, the baseline 3 is appropriate.

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 clearly states the tool returns a tracked product-page link for the buyer to review and buy or download a free kit. It names the specific resource (product-page link) and the action (return), and distinguishes it from order creation or payment. The title reinforces this, and the description adds enough specificity to differentiate it from siblings like get_kit or search_kits.

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 implies when to use this tool: when you need a link for a buyer to review/purchase or download a free kit. It explicitly states what it does NOT do (does not create an order, charge money, accept terms, or provide paid files), which helps an agent avoid using it for purchase completion. However, it does not explicitly name alternatives or conditions for when to use get_kit or search_kits instead, so it falls short of a 5.

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