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

Annotations already cover read-only/idempotent/non-destructive, and the description goes well beyond them: it discloses the return payload (specs, calculated rating differences, same-currency price observations, missing inputs, canonical URL) and, critically, limits the interpretation of price data as dated arithmetic comparisons rather than verified savings, plus explicit non-verification of stock, delivery, tax and medical suitability.

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 sentences, front-loaded with purpose then returns then caveats; the disclaimers are dense but each clause earns its place by preventing misreading of the price output. Slightly list-like in the final sentence but not padded.

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 and minimal annotations, the description carries the full burden and does so: it enumerates what is returned, what is computed vs observed, and what is explicitly not verified, leaving no material gap for correct invocation.

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%, so the baseline is 3, but the description adds real meaning: the parameters are catalogue slugs requiring exact matches, not arbitrary names or free-text identifiers as the terse schema text ("Identifier of the first racket") suggests.

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 opens with a specific verb+resource ("Compares two exact catalogue slugs") and the modifier "exact" distinguishes it from the search/search_rackets siblings, which handle loose lookup. An agent can tell this is a head-to-head comparison tool, not a single-item fetch like get_racket.

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?

The requirement for "exact catalogue slugs" implicitly tells the agent it must resolve identifiers first (via search/get_racket), but no alternative tool is named and no when-not-to-use condition is stated. Usage is inferable rather than explicit.

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