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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds useful context (data source date-holidays CC BY 3.0, coverage breadth, localized names), but never states what the tool actually returns (a boolean, a holiday name, a list?) which is the key behavioral fact for a 'check' tool with no output schema.

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?

The description asks 'Is this date a public holiday?', then 'Is it a holiday?', then again "plus 'is this date a holiday?' check" — three near-duplicate restatements of the same question before any new information. The redundancy wastes the most valuable front-loaded space.

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 no output schema, the description carries the burden of explaining the return shape, and it never does. It also fails to differentiate from the sibling 'public_holidays', so an agent cannot reliably pick this tool or predict what it hands back.

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%, so the schema already documents country (ISO code), state, and date (YYYY-MM-DD). The description adds only the incidental detail of 'any year' and 'localized names', which maps loosely to country/state but provides no syntax or format beyond the schema. Baseline 3 applies.

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 makes the operation clear: a yes/no check of whether a date is a public/bank holiday, with stated scope (100+ countries, states/regions, any year). However, it never distinguishes itself from the sibling tool 'public_holidays', leaving the agent to guess which one produces a boolean check versus a holiday list.

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?

There is no when-to-use guidance and no mention of alternatives, despite the near-identical sibling 'public_holidays' sitting right next to it. An agent has no stated rule for choosing between the two.

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