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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real context beyond that: unavailability records may be self-marked OR marked by someone else, which tells the agent what population of records it will see, plus the concrete API endpoint.

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?

One front-loaded sentence carrying the purpose and the usage trigger, followed by an endpoint reference. Nothing is padded, though the raw API path is marginally redundant for an agent that already has the tool interface.

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?

For a one-parameter read tool this covers what to call and why. However, with no output schema, the description never indicates what the returned time records look like or whether results are paginated, leaving the agent guessing about the response shape.

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 the single parameter (employee_id) is already documented in the schema. The description only restates it via the URL template, adding no format or constraint detail beyond the schema's minimum/maximum.

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 (List) and resource (times one employee marked unavailable to work), scoped to a single employee. It is immediately distinguishable from the sibling deputy_add_unavailability, which is the write counterpart.

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?

"check before rostering them" gives a concrete workflow trigger for calling the tool, which is better than generic guidance. It stops short of naming alternatives or stating when-not to use it (e.g., vs. deputy_list_shifts), so it does not reach the top band.

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