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

With no annotations, the description carries the behavioral burden; it does disclose the key rule (shifts to previous/next business day on weekends/holidays) and the $0.01 USDC x402 payment requirement. It does not spell out the return value or default calendar, but 'calculator' makes the read-only, pure-function nature clear.

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 tight sentences: purpose, example, adjustment rule, and pricing. Every clause earns its place and the key domain term and behavior are front-loaded.

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 6-parameter tool with no output schema, the description plus a fully documented schema is nearly sufficient. It could explicitly state that the result is a date string and mention the 'none' adjust option, but those are minor given the schema's clarity and the obvious output of a due-date calculator.

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%, so the baseline is 3, but the description adds a domain example ('month-end close paid end of next month') that clarifies closing='end', payDay='end', and monthOffset=1. That enriches the schema's bare parameter definitions.

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?

Description names a specific resource ('Japanese payment terms (shimebi/shiharaibi) calculator') and gives a concrete example (month-end close paid end of next month). This clearly separates it from sibling tools like is_business_day or add_business_days, which answer different questions.

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 payment-terms example implies when the tool should be used, but the description never explicitly says to prefer it over add_business_days/is_business_day/list_holidays or states when not to use it. That is implied usage rather than active routing.

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