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

With no annotations provided, the description carries the full behavioral burden. It discloses that the calculation uses the current silver spot price and returns total ASW in troy oz and grams plus melt value in both USD and CAD. It does not discuss error cases or spot-price sourcing, but the core behavior and outputs are clearly described.

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 description is long but earns its length: the coin-type enumeration is redundant with the schema yet strengthens purpose clarity, and the usage and return paragraphs are tightly written. It is well-structured and front-loads the core action, though it could trim the repeated coin list slightly.

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?

There is no output schema, so the description correctly explains the return values (ASW in troy oz/grams, melt value in USD/CAD) and the input pattern (coin_type + quantity OR face_value). It lacks an explicit statement about what happens if both quantity and face_value are provided, but for a tool this size the description is substantially complete.

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% with detailed per-preset ASW values, so the baseline is 3. The description adds meaningful usage semantics beyond the schema: it clarifies that quantity and face_value are alternatives ('either... or'), gives a concrete example ('face_value 2.50 for a roll of dimes'), and explains that coin_type selects the preset. This elevates the score to 4.

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 clearly states the verb 'Calculate' and the resource 'melt value of junk silver coins', listing all supported coin types with their composition and date ranges. It is specific enough to be distinguished from the more generic sibling names, but it does not explicitly name or differentiate from 'calculate_melt_value', so it falls short of the strict 'distinguishes from siblings' bar.

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?

The description gives concrete usage context: it scopes the tool to junk/constitutional silver presets and instructs the agent to provide 'the coin type plus either a quantity of coins or a total face value', with an example. It does not explicitly exclude alternatives or say when NOT to use this tool, but the domain is clearly bounded.

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