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

No annotations are provided, so the description carries the full burden. It does add two useful non-obvious facts: output includes the working, and each call costs $0.01 USDC on eip155:8453. It says nothing about rounding, currency assumptions, or error behavior for invalid inputs.

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 sentences, front-loaded with the actual capability, which is good. The middle sentence is redundant with the first and grammatically broken, so it does not earn its place.

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?

For a two-parameter pure-computation tool with full schema coverage and no output schema, the definition covers what it computes, what it returns, and even the call cost. Only edge-case behavior for malformed input is unaddressed.

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 100% (both parameters documented as 'Original price' and 'Discount %'), so the baseline is 3. The description's 'price and percent-off discount' phrasing confirms the percent basis but adds no unit, range, or format detail beyond the schema.

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 final sale price and savings from price and percent-off, plus 'with the working shown'. This is distinguishable from the sibling percentage_calculator and vat_calculator by the percent-off/sale-price framing, though the description never names those neighbors to make the boundary explicit.

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 second sentence, 'Use this when an agent needs to sale price and savings from a percent off,' is an ungrammatical restatement of the purpose rather than genuine guidance. There is no when-not, no prerequisite, and no named alternative for the closely related tip/percentage/VAT calculators.

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