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

readOnlyHint=true already covers the safety profile, so the description's added value is elsewhere: it discloses that the call is free and does not count against the call quota, which is cost/rate-limit information an agent cannot get from annotations. It also implicitly documents the response shape. Minor gap: it does not say whether the data is cached or how large the result set typically is.

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 short sentences with zero padding: scope and coverage first, then return fields, then the prerequisite workflow instruction, then cost. Front-loaded and every sentence carries distinct 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?

There is no output schema, so the description must explain return values — and it names all four returned fields. Combined with the single well-documented optional parameter, the readOnly annotation, and the explicit prerequisite ordering plus billing note, nothing an agent needs to call this 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 coverage is 100% and the single optional market parameter is already well documented in the schema, including its reference to the returned market field. The description mentions that results span multiple markets and include a market field, which corroborates the parameter's meaning, but adds no filtering syntax or behavioral detail beyond the schema. 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?

States a specific verb and resource: gets the list of on-sale precious-metal varieties in GoldAPI, enumerates the covered metals (gold/silver/platinum/palladium) and states the spot/futures scope. It also lists the fields returned (goldId, name, market, category), which clearly separates it from the sibling quote-fetching tools get_history/get_kline/get_realtime.

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?

Gives an explicit routing rule: before querying quotes, call this tool first to obtain goldId. That tells the agent exactly where this tool sits in a multi-step workflow. It stops short of naming the sibling tools directly or stating any when-not-to-use condition, so it isn't a full 5.

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