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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the description's job is to add context, and it does: live website quotes are included, an optional buyer-offer comparison exists, and a prefilled PDF-report link is produced. It does not explain quote freshness, caching, or failure behavior, which would push it higher.

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?

One dense sentence with the core purpose front-loaded and no filler. It is packed tightly enough that the input list and the feature list run together, but no sentence is wasted.

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 not be described, and the annotations carry the safety profile. However, the most critical unknown — what string to pass as 'coin' (name, slug, catalog ID?) — is unaddressed in both schema and description, and spot/fees are undefined.

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% across 7 parameters, so the description must compensate. It covers coin, quantity/rolls (including the mutually-exclusive pairing implied by 'quantity or standard rolls'), and measuredGrams, plus hints at offer, but leaves spot and fees completely unexplained — a meaningful gap for a pricing tool.

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: computes melt value and fine-metal content from a native coin issue plus quantity/rolls/measured grams. The input basis ('native coin issue') implicitly separates it from the generic calculate_melt_value and calculate_penny_nickel siblings, but no sibling is named explicitly.

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 listed inputs; there is no statement of when to pick this over calculate_melt_value, calculate_penny_nickel, or find_coins. Nothing warns about prerequisites (e.g., that the coin must be a recognized native issue) or what happens when the coin is unknown.

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