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 usefully discloses the default start behavior and the shape of returned rows (original_date for shifted observances, half-day and early-close details), which is valuable given there is no output schema. However, it says nothing about error behavior for invalid calendar codes, whether results are bounded or paginated, or the read-only nature implied by a lookup.

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 tightly packed sentences with the resource stated first, then parameter behavior, then return shape. No filler or restatement of the name. The middle clause about historical and forward dates is compressed but still parseable.

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 simple parameters, no annotations, and no output schema, the description covers the essentials, including return-field semantics that would otherwise be invisible. It falls short on invalid-code handling and on routing among the numerous holiday siblings, which for a tool in this dense a family is a real gap.

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 and it largely does: calendar is a code with a worked example, start is a date with a documented default of today and a historical-range use case, and end delineates a forward bound. All three parameters gain meaning beyond their bare type/format declarations.

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 concrete resource (holidays) scoped to a single calendar identified by a code, with a concrete example (USD.FX). It does not explicitly distinguish itself from siblings such as bank_holidays, fx_market_holidays, or settlement_holidays, so an agent must infer that this is the generic per-calendar variant.

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?

Guidance is present but parameter-oriented: it explains that start defaults to today and that an earlier start or an end bound is used for historical or forward ranges. There is no explicit statement of when to choose this tool over the many holiday-related siblings, and no reference to list_calendars for discovering valid codes.

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