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

Beyond the annotations (readOnly, idempotent, non-destructive, open-world), the description discloses cost ($0.01 USDC per successful call via x402 on Solana) and an equivalent HTTPS endpoint — material traits an agent must know before invoking. It stops short of describing response shape or failure behavior.

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 capability statement is front-loaded in a single dense sentence followed by a short pricing/transport sentence; nothing is wasted. The first sentence is long and enumerates four ops inline, but that density is informative rather than filler.

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 9-parameter, multi-mode tool with no output schema, the description covers coverage breadth, op semantics, weekend rules, cost and transport. The notable gap is that return values for each op are never sketched, which matters more here since no output schema exists to carry that.

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 every parameter is already documented with format and op binding, which sets the baseline at 3. The description reinforces weekend configurability (e.g. fri,sat), subdivision scoping and the 100+ country coverage, but adds little syntax or edge-case detail beyond the schema.

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+resource (public holidays for 100+ countries) plus the four distinct operations it performs in one call: list, add/subtract, is-business-day, count. This is far more specific than the title 'Holidays Business Days' and no sibling tool covers holiday calendars or business-day math.

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 description enumerates the four operation modes with the inputs each implies (year for listing, date+days for add, date for is-business-day, start/end for count), giving clear context for selecting an op. It does not state explicit exclusions or point to an alternative tool, but none of the siblings overlap.

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