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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description adds real value by disclosing that prices are caller-supplied rather than fetched, and that results include constituent weights, face value, and a prefilled PDF-report link. It still does not describe units handling for measuredGrams versus count or validation failures.

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 dense sentence that front-loads the action and resource, then the input modes, then the pricing convention, then the outputs. No filler, though the packing makes the output clause feel tacked on.

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 seven parameters, a conditional oneOf schema, and zero schema description coverage, the definition leaves the most error-prone part — which parameters are legal for 'penny' versus 'nickel' — entirely undocumented. The existing output schema means return values need not be explained, but the input contract is still incomplete.

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 0%, so the description must carry the burden, and it only glosses 'count or measured total grams' and 'base-metal prices in USD per ordinary pound'. It never explains the critical oneOf branch: pennies require alloy+zinc and forbid nickel, nickels require nickel and forbid alloy/zinc, nor what the alloy enum values brass/zinc mean.

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 (metal value of penny/nickel alloy coins) and pins the input modes (count or measured grams) plus the pricing basis (manual base-metal prices in USD/lb). An agent can distinguish it from calculate_melt_value or calculate_coin_value by the coin-specific scope, though no sibling is named.

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 only implied by the phrase 'from count or measured total grams', which suggests the two input modes, and by 'explicit manual base-metal prices', which hints this is not a live-price lookup. Nothing states when to prefer this over calculate_melt_value or calculate_coin_value, and there are no conditions or exclusions.

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