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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds the meaningful business context that the lookup is free and neither creates checkout nor charges the buyer. It does not describe return shape or any rate/refresh behavior, so it stops short of full transparency.

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?

Three tight sentences, front-loaded with the free/read-only nature of the call, followed by outcome ('returns packages and prices') and then routing guidance. No redundant or throwaway text.

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 one-parameter, no-output-schema tool, the description covers purpose, side-effect profile, and workflow placement. The only gap is the precise return structure (package fields, price format), which an agent must infer from the prose.

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 100% and the single search_id parameter is fully documented in the schema itself. The description only restates that the exact search_id from search_matches should be passed, adding no syntax or format detail beyond the schema, so the baseline 3 applies.

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?

Specific verb and resource: a free, read-only pricing lookup for unlock packages tied to an existing search_matches search_id. It distinguishes itself from the checkout sibling by explicitly stating it does not create checkout or charge the buyer.

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?

Explicit routing: use create_checkout only after a buyer picks a package, and use search_matches first if no search_id exists. Both the successor and the prerequisite are named with their selecting conditions.

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