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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered and 'Read-only' in the description is largely redundant. The description does add some behavioral context by flagging that caching and limits exist, but the reference to 'GET /v1/holidays' is a pointer rather than a concrete disclosure of what those limits are.

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 compact sentences, front-loaded with purpose and scope, then reader-facing notes. The only wasted clause is 'Read-only', which duplicates readOnlyHint=true already exposed in annotations.

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?

An output schema exists, so return values need not be explained, and the description covers the key constraints: one country, optional region, single year, bounded range, and selectable holiday types. The only omission is any note on how regional holidays combine with country defaults, which the schema only partially implies.

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 100% (year range, ISO alpha-2 country, region code examples, types comma list all documented in-schema), so the schema carries the parameter burden and baseline is 3. The description only restates the year range and country/region relationship, adding no format or interaction 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 and resource ('List the public ... holidays'), plus the exact scope: one country, optional region, one year, bounded 2020-2035. The declared return contents (local names, types, official source links) further pin down what the tool produces, and no sibling tool (business-day math, country listing) overlaps with it.

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?

Usage is implied rather than stated: the description notes holidays can optionally include bank/observance types, which nudges toward the 'types' parameter, but there is no explicit when-to-use or when-not-to-use guidance. Given the siblings are arithmetic utilities rather than holiday alternatives, this is adequate but leaves the call/no-call decision to inference.

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