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

Despite the annotations already indicating mutation and non-idempotency, the description adds substantial behavioral context: each call produces a new 7-day link, the link reflects basket contents at opening time, an empty basket errors, payment details stay invisible to the assistant, and no order is placed until the customer pays. This goes well beyond what the annotations convey.

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 front-loaded with the primary use case, then flows logically through prerequisites, return behavior, lifecycle details, and error handling. Every sentence contributes essential information without redundancy.

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?

Even though an output schema exists and is not described, the definition covers prerequisites, edge cases (empty basket), link behavior, security concerns, and post-checkout state. It is fully sufficient for an agent to invoke 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?

The schema already fully documents basket_id, so the description's restatement of when to include it adds only marginal value. The baseline of 3 is appropriate given 100% schema coverage.

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 states a specific action (generate a secure checkout link for the current teas.co.uk basket) and distinguishes itself from the sibling checkout_session by naming it and its different purpose. An agent can immediately tell what this tool does.

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?

It specifies the exact condition for use ('when the customer is ready to buy what is in their basket'), explains when to omit or include basket_id based on host behavior, and explicitly names checkout_session as the alternative for buying specific products without the basket.

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