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 disclose useful behavior: weekends are excluded, real public holidays for the supplied country are fetched from Nager.Date and excluded, and the response includes a weekend/holiday breakdown. It omits date format expectations, invalid-range handling, and network dependency failure modes, so it is helpful but incomplete.

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 dense sentences with the core behavior front-loaded and zero filler. The trailing x402 price note is relevant but appended in a slightly clipped way rather than integrated.

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 three-parameter tool with no annotations and no output schema, the description covers purpose and the exclusion behavior adequately, but leaves the caller guessing about date format, ordering, edge cases (start after end), and failure behavior when the holiday service is unavailable.

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 three parameters are already documented in the schema. The description reinforces the country/holiday linkage and the start/end date range but adds no format, range, or ordering semantics beyond it — baseline 3.

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 ('Count business days (Mon–Fri) between two dates') plus the distinguishing feature (weekend and holiday breakdown, holidays via country code). It is clearly distinct from the generic siblings like calculators_date_difference_calculator, though it never names that sibling explicitly to route the agent.

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 description — you call it when you need business-day counts rather than raw date differences — but there is no explicit when-to-use/when-not guidance or named alternative, leaving the agent to infer the selection rule.

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