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

No annotations are supplied, so the description carries the full behavioral burden; it does disclose the notable default that start falls back to today, which is real behavioral value. It omits what the response contains (list of dates? count?), what happens when end is omitted, and any timezone or weekend-inclusion semantics for a tool whose whole output is date semantics.

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?

Three short sentences, each with a distinct job: define the resource, give the use case, state the default. Nothing is padded and the most important identification detail (ISO 4217 / non-clearing) is front-loaded.

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 simple three-parameter lookup with no output schema, an agent still does not know what comes back (dates, count, calendar objects) or the exact scope of "non-clearing" (weekends included? currency-specific holidays only?). The core identity and default are covered, but the return-shape gap is a meaningful omission for a tool this small.

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 currency as an ISO 4217 code with an example and clarifies the start default behavior beyond the schema's null default. The end parameter receives no explanation at all, and date format expectations beyond the schema's format field are not addressed.

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 states a specific resource with a definition ("days the currency cannot clear or settle") and scopes it to ISO 4217 currency codes, which clearly separates it from date-arithmetic siblings like add_business_days. However, it never distinguishes this from close siblings such as settlement_holidays, bank_holidays, or fx_market_holidays, so an agent cannot route between them on the description alone.

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?

"Use to validate FX value dates" gives one concrete usage context, which is genuine guidance rather than nothing. It provides no when-not conditions and does not name any sibling as the alternative for overlapping queries (settlement vs. bank vs. FX market holidays), leaving the selection decision implicit.

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