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

With no annotations, the description carries full burden, and it does add real behavioral context: cost ($0.01/call in USDC on Base, eip155:8453), the x402 payment path (params._meta["x402/payment"]), and the backing HTTP endpoint. However, it never explains how the caller selects between the four advertised operations — the schema has no mode selector and no 'N days' parameter — leaving a significant unexplained gap in how the tool actually behaves.

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 purpose is correctly front-loaded in the first sentence, but the pricing and endpoint are stated redundantly — the $0.01 x402 price appears twice in slightly different wording — wasting space in a short description.

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?

No output schema and no annotations, so the description must explain results and mode selection, and it does neither: it never says what is returned for each of the four operations (boolean, date, integer, list). Worse, the schema exposes only country/start/end, so the advertised 'add N business days' and 'count between dates' capabilities have no visible parameter to drive them — an agent cannot tell how to invoke those modes.

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 country/start/end are already documented (including the US federal vs UK England & Wales enum semantics), which sets the baseline at 3. The description adds nothing beyond that and does not clarify whether 'end' is inclusive or how start/end are interpreted in the 'add N business days' and 'is a business day' modes, where the range meaning is unclear.

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 opening sentence names the domain (US/UK public holidays and business days) and enumerates four concrete operations, so an agent knows exactly what the tool covers. It does not, however, distinguish itself from the sibling tools bizcal_api__day, bizcal_api__add, bizcal_api__between and bizcal_api__year, which appear to expose the same four operations individually.

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?

There is no guidance on when to call this combined tool versus the four single-operation siblings (day, add, between, year), nor any prerequisites or exclusions. The agent must guess based on the name alone.

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