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

Annotations already declare this a safe, idempotent, closed-world read, so the bar is lower; the description still adds real value by disclosing the returned fields (rate per gram, total, spot quote time) and the crucial caveat that the figure is non-binding until weighing and XRF testing. It does not mention rate refresh cadence or quote staleness beyond 'today's published rate'.

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 dense sentences, front-loaded with purpose, then input format, then return shape and caveat. No filler; each sentence carries information the agent cannot get elsewhere.

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 present, the description carries the return-value burden and discharges it by naming the rate per gram, total and spot quote time. Combined with full parameter coverage and the estimate-vs-final caveat, an agent has everything needed to call and interpret this tool.

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 genuinely extends the schema: it enumerates purity forms across carats (9–24), hallmark numbers (375, 585, 750, 916, 999, 925, 958, 800) and words (sterling, fine, bullion) well beyond the schema's few examples, and clarifies that weight_grams is the item as placed on the scale.

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+resource ('what we would pay for a given weight of gold, silver or platinum') and scopes it to today's published rate, so the agent knows it produces a live quote rather than a stored price. It does not, however, distinguish itself from siblings like get_buy_price or get_sell_price, leaving the boundary to inference.

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?

Usage is implied rather than stated: the tool estimates a payout for a weight the customer already has, and the closing note that 'the final figure follows weighing and XRF testing' signals this is a pre-transaction estimate. No explicit when-to-use, when-not-to-use, or named alternative (get_buy_price) is provided.

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