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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond that by disclosing the returned fields per shop and the behavioral effect of the size parameter (adds in/low/out status). It stops short of covering ordering, currency normalization or completeness of the shop list.

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?

A single dense sentence with zero filler, and the core action plus output contents are front-loaded before the optional size qualifier. Slightly over-packed but every clause carries 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?

With no output schema, the description compensates by enumerating the returned per-shop fields, and it explains the size parameter's effect on the result. For a two-parameter read tool with full annotations, nothing an agent needs to invoke it correctly is missing.

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 100%, so both parameters are already documented in structured form, including the slug pattern and its source tools. The description's "optionally for one size" restates the optionality without adding format or semantics beyond the schema's in/low/out explanation.

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?

"Lists the shops that sell one product" gives a specific verb and resource, and the sentence enumerates exactly what each entry contains (price, strike price, stock, link). It does not name or contrast with any sibling, so an agent must infer that this is the product-level detail view versus search_sneakers/get_deals.

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 only implied: "optionally for one size" signals when to pass the size parameter, and the slug's origin is documented (though in the schema, not the description). There is no statement of when to call this instead of search_sneakers or get_deals, and no prerequisites or exclusions.

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