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

Annotations already establish this is a read-only, open-world operation, so the bar is lower. The description adds genuinely new behavioral context: coverage breadth (100+ countries), non-standard Friday-Saturday weekend handling, and a per-call cost of $0.002 USDC via x402, which is material for an agent deciding whether to invoke it.

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, front-loaded with the core capability before the pricing note, with zero filler. The parenthetical use-case list is compact and informative rather than wasteful.

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 four-parameter tool with 0% schema coverage and no output schema, the description leaves too much unspecified: which parameter combinations are valid, what the return value looks like (a date vs an integer count), and required vs optional inputs. The mode/parameter mapping gap is the most serious omission.

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 0% and none of the four parameters (add, end, start, country) are documented anywhere. The description implies a mode split (add-offset vs start/end range) but never maps parameters to modes, nor specifies date format, whether `country` is required, or whether country accepts ISO codes or names.

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 names specific operations (add/subtract working days, count working days between two dates) on a concrete resource (business days across 100+ countries), so the agent knows exactly what the tool computes. It does not explicitly differentiate itself from siblings like `holidays`, `business_counts`, or `time`, leaving that inference to 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?

It gives example use cases (due dates, settlement, SLAs) which implies when the tool is useful, but never states when to prefer it over `holidays` (holiday lookup) or `time`/`timestamp`. No prerequisites or exclusions are given, so usage is implied rather than directed.

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