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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the trait that matters most here: the returned dates are a usual pattern, not official, because councils and schools set their own — plus a mandatory disclaimer to relay. That is real behavioral context beyond structured fields.

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 sentences: the first establishes what is returned, the second immediately qualifies accuracy and prescribes the disclaimer. The non-authoritative caveat is front-loaded where it cannot be missed, and no sentence is filler.

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?

Output schema exists, annotations are rich, and both parameters are fully described in schema. The one thing an agent must know before presenting this data — that the dates are indicative and users must verify — is stated explicitly, so nothing critical is missing.

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 with range and default, region as a three-value enum), so the schema does the work. The description's 'a UK nation in a year' merely mirrors both parameters rather than adding format or selection nuance, which is fine but earns baseline-plus only.

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 resource (typical state-school holiday dates: half terms, Easter, summer, Christmas) scoped to a UK nation and a calendar year. That resource is unmistakably distinct from the sibling get_bank_holidays, so an agent can route without opening a schema.

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 description tells the agent how to present results ('always tell the person to check their school's term dates') and implies a planning/approximation context, but never names an alternative tool or an explicit when-to-use condition versus get_bank_holidays or plan_leave_year. Usage is left to inference.

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