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

Annotations already cover read-only/idempotent/non-destructive behavior, so the bar is lower. The description adds useful context beyond the annotations: retailer accreditation scope, pack-by-pack organization, ordering by what the owner pays, inclusion of price-read dates, and prescription flagging.

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 around 70 words and every sentence carries functional information; examples and boundary statements are useful rather than redundant. It is slightly dense and the first sentence is a long noun phrase, but it is still easy to scan.

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 read-only lookup with no output schema, the description tells the agent what the result contains (retailers, links, dates, pack-level prices), how results are sorted, and what the tool will not do. Nothing essential to a correct call 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 coverage for the single 'name' parameter is 100%, so the baseline is 3. The description adds value by giving concrete example values ('Bravecto' or 'Apoquel 16 mg') and by reinforcing that the search key is the medicine's name.

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 names the exact resource (prices for a named veterinary medicine from VMD-accredited UK online retailers) and the output (retailer links, pack-level prices, read date). This clearly separates it from sibling tools like procedure_prices and provider_details, whose domains are procedures and provider details, not medicine prices.

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 how to call it ('Search by the medicine's name') and gives examples, and it excludes recommendation requests ('Does not suggest medicines or doses'). However, it never names sibling tools or states when to choose this over procedure_prices or provider_details, so routing guidance is only implied.

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