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

No annotations are provided, so the description carries the burden. It does add useful disclosure: the return value (final price, savings, working) and an explicit x402 cost of $0.001/call in USDC on eip155:8453, which is real behavioral context. However, it says nothing about rounding, currency assumptions, or determinism/purity of the computation.

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 tight sentence describing the computation, followed by a separated pricing note. Front-loaded with the core purpose and free of filler, though the pricing tail is only loosely tied to the functional description.

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?

No output schema exists, and the description compensates by naming the return values (final price, amount saved, working shown). For a two-parameter, single-purpose calculator with full schema coverage, this is close to sufficient; only edge-case behavior (rounding, currency) is left unspecified.

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% with only two parameters ('price' and 'discount'), so the schema fully documents them. The description's mention of 'any price and percent-off discount' confirms the unit (percent) but adds little beyond the schema. Baseline 3 applies.

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: calculate final sale price and amount saved given price and percent-off discount. It is clearly distinguished from most siblings (tip, VAT, loan), though it does not explicitly contrast with calculators_percentage_calculator. The 'working shown' clause also hints at the response content.

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?

No when-to-use guidance, no mention of when a plain percentage calculator would be preferable, and no prerequisites stated. The pricing note describes cost, not usage context.

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