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

With no annotations, the description carries the full behavioral burden. It does add real context — the weekend-skipping rule, optional holidays, and a cost of 1 credit per call — but omits error behaviour, how negative or out-of-range add_days is handled, and the fact that only 'start' is required.

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: capability first, cost second. No filler, no restatement of the tool name, and the most important information is 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?

There is no output schema and no annotations, so the description is the only source of truth. It explains the two modes and the holiday/weekend behaviour but never says what is returned (a count versus a shifted date) or how the competing 'end'/'add_days' inputs resolve, which is a notable gap for a 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 description coverage is 0%, so the description must compensate. It conceptually maps all four parameters (two dates, add_days, optional holidays), but adds no format detail (the YYYY-MM-DD pattern), no sign semantics for add_days, and no mutual-exclusivity rule, leaving meaningful gaps for a four-parameter tool.

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 ('Count working days between two dates or add working days to a date') and clarifies the core rule of skipping weekends and optional holidays. It is unambiguous on its own, though it never names or contrasts itself with adjacent calculator siblings such as tempo_calculator or timecode_calculator.

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?

Two operating modes are implied ('between two dates' vs 'add working days to a date'), which suggests when each branch applies, but there is no explicit statement that 'end' and 'add_days' are alternatives or mutually exclusive, nor any prerequisites beyond the implicit start date. Usage is inferable but not spelled out.

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