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 'Read-only' sentence adds little. The description earns credit for disclosing the calculation basis and its limits (spot-to-spot only, no premiums or buy-back spreads), which prevents misinterpretation of the numeric output.

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 definition leads with what the ratio is, then the conversion behavior, then scope limits, then the usage cue. All content is relevant; it is dense with colons and semicolons 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?

An output schema exists, so return values need no explanation, and the description covers basis, optionality, direction, and scope limitations. Only minor gaps remain, such as which spot source or timestamp underlies the ratio.

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 the key semantic the schema cannot express: both parameters are optional, and supplying neither yields just the ratio, while supplying one selects the conversion direction and the output unit (gold to silver or silver to gold). This is meaningfully more than the field-level descriptions.

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 (the gold/silver ratio, defined as ounces of silver one ounce of gold buys at spot) and a specific operation (optional conversion in either direction). It is clearly distinct from sibling price tools such as get_spot_prices, get_premiums, and get_buyback_price, which it implicitly excludes.

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 gives an explicit trigger ('Use when the user asks for the gold/silver ratio or a spot-to-spot conversion') and an explicit exclusion ('Spot-to-spot only; premiums and buy-back spreads are not included'), which steers the agent away from premium or buy-back tools. It does not name a specific sibling alternative for those excluded cases, keeping this below a 5.

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