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

With no annotations, the description must carry the behavioral burden. It discloses the core additive rule and mentions calendar versus business days, but omits the default mode, allowed mode values, weekend/holiday handling, date parsing rules, and return format.

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 definition is a single front-loaded sentence with no filler, making the core formula immediately visible. The leading 'PRO.' is unexplained, but otherwise the structure is efficient.

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 tool with no annotations, no output schema, and low schema description coverage, the definition leaves important invocation details unspecified. An agent would have to guess exact mode values, default behavior, date format, and whether holidays are considered.

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 only 25%, so the description needs to compensate. It identifies the roles of start, days, and mode through 'start + N calendar or business days,' but does not specify date format, numeric constraints, or exact mode strings.

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 operation: computing an invoice due date by adding N days to a start date, with calendar or business-day modes. It is clear what the tool does, but it does not distinguish itself from the overlapping sibling tool business_days.

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 phrase 'Invoice due date' implies a use case, giving some context for when the tool applies. However, it provides no explicit when-to-use guidance, exclusions, or routing versus siblings such as business_days, next_holidays, or year_planner.

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