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

With no annotations, the description carries the behavioral burden and does reasonably well: it discloses the calculation logic (same-day before cutoff, else next bank business day) and, unusually and usefully, the cost model ($0.01 USDC via x402). It does not state error handling or the exact return format, hence not a 5.

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?

Two compact sentences: the first frames the question, the second delivers the rule and the price. Front-loaded and waste-free, with only a minor rhetorical lead-in.

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 must convey the return value; it says a value date is returned but not its format (date string, ISO, timezone). Given a zero-required-parameter calculator, the rule, defaults, and price are otherwise sufficient for correct invocation.

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%, so the baseline is 3. The description restates the default cutoff of 15:00 JST but adds no syntax, constraint, or interaction details (e.g., how extraDays composes with the cutoff rule) beyond what the schema already documents.

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 states a specific verb and resource — it returns the value date for a Japanese bank transfer — and the opening question frames the exact scenario. It is clearly distinguishable from generic siblings like add_business_days or is_business_day, though it never names those siblings 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 implied by the scenario framing (a bank transfer credit question) and the stated rule, but there is no explicit when-to-use or when-not-to-use guidance relative to alternatives such as payment_due_date or add_business_days. The agent must infer the selection context.

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