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

No annotations exist, so the description carries the full burden. It usefully notes that start resolves to today when omitted (which the schema does not reveal, since its default is null), but it says nothing about what happens when end is null, whether an empty list is returned, or how results are shaped — for a read of holiday data with no annotation coverage, that leaves the agent guessing.

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 short sentences, front-loaded with the domain definition and appended with the one behavioral default. Nothing is padded, though the phrasing is clipped enough that the missing operation verb and value guidance aren't merely trimmed for brevity.

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?

With three parameters, zero schema description coverage, no annotations and no output schema, the definition should at minimum name the accepted payment systems and describe the returned interval. It only covers one default, so an agent cannot call this reliably without trial and error.

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 explains the start default, but adds nothing about which payment_system values are accepted (no enum, no pointer to list_payment_systems) and nothing about the meaning or bounds of end.

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 defines the resource concretely ("Payment system holidays (e.g. TARGET2, FEDWIRE): days the system does not process or settle"), and the named examples implicitly separate it from sibling tools like bank_holidays, trading_holidays and fx_market_holidays. It never states an explicit verb such as "list" or "return", so the operation is inferable rather than declared.

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 parenthetical examples of payment systems imply the domain of use and thereby partially disambiguate it from the many holiday-family siblings. However, there is no explicit statement of when to prefer this over bank_holidays or settlement_holidays, and no prerequisites or exclusions are given.

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