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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint false and closed-world scope, so the safety profile is covered. The description adds useful behavioral context by disclosing the three data components returned (typical/lowest premium today, 2-year median, lowest-premium product), but says nothing about data freshness, update cadence, or how unsupported formats are handled. With an output schema present, this is adequate but not rich.

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 sentence with the core value proposition front-loaded ('Today's typical and lowest premium over the Ask spot') and the return components trailing. The parenthetical format list is somewhat long but earns its place by concretizing 'standard coin and bar format'.

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 tool with annotations and an output schema, the description covers what is returned well. However, it never states the behavior when the optional metal parameter is omitted, which is the one decision an agent must make when invoking it.

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% and the single optional 'metal' parameter is fully documented in the schema with an enum. The description does not mention the metal filter at all, so it adds no meaning beyond the schema; the baseline of 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?

The description names a specific resource (premium over Ask spot) and enumerates exactly what is returned: today's typical and lowest premium per standard coin/bar format, the 2-year median, and the lowest-premium product. It is clear what the tool yields, though it does not explicitly contrast itself with siblings like get_spot_prices or get_product.

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?

There is no explicit guidance on when to call this versus get_spot_prices, get_price_history, or get_product, and no mention of prerequisites or exclusions. Usage must be inferred from the subject matter alone.

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