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

Annotations already declare readOnlyHint/non-destructive, so the bar is lower, and the description still adds real behavior: results are oldest-first and capped at 1,000, and a holiday removes the whole working day from everyone's capacity while a weekend holiday removes nothing. It does not explain pagination past the cap, but the cap itself is disclosed.

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?

Front-loaded with what is listed and in what order, with the limit and returned fields immediately after. The capacity parentheticals are slightly chatty but they carry genuine meaning about what the data implies.

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 usefully enumerates the returned fields and the result cap, and the Pro requirement is noted. Only the default range behavior when from/to are omitted is unaddressed, a minor gap for a two-param read tool.

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 coverage is 100% and both from/to are fully documented in the schema with date format. The description adds no additional parameter semantics such as default range behavior when neither bound is supplied, so 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?

Specific verb+resource: 'Lists the holidays on the user's calendar', plus ordering ('oldest first') and returned fields (day, name, weekend flag). It distinguishes itself from siblings like list_time_off by framing holidays as capacity-affecting, though the differentiation is implicit rather than by name.

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?

'A Pro feature' is an explicit prerequisite, and the capacity framing makes the context of use clear (Workload planning). It stops short of naming alternatives such as list_time_off or stating when not to use it.

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