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

Annotations already flag readOnlyHint and openWorldHint; the description adds 'Never cached', clarifies the result is not the final payable amount, and notes checkout determines the true total. This goes beyond the structured annotations, though it does not address rate limits or response format.

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?

Four sentences, front-loaded with purpose, and all information is relevant. It is compact but slightly dense with warnings at the end.

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 no output schema, the description could do more to explain what the response contains, and five optional parameters are unexplained. But the core call path (variant_ids + quantity) is clear enough to be minimally viable.

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 coverage is only 29%, and the description only explains variant_ids and quantity, which the schema already documents. The remaining five parameters (journey_id, match_type, selected_sku, result_set_id, selected_handle) are left unexplained in both schema and description.

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 verb ('confirm'), a clear resource ('live base catalog unit price and merchandise line total'), and a usage stage ('before cart handoff'). It distinguishes itself from shipping/cart-finalization tools by explicitly excluding discounts, shipping, and tax, though it does not name sibling tools.

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 tells the agent when to use the tool ('Use to confirm ... before cart handoff') and what it is not for (discounts, shipping, and tax are not evaluated). Missing explicit alternatives, so not a 5.

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