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

The description is consistent with readOnlyHint=true and confirms this is a read of existing unavailability entries, so no contradiction. Beyond that it adds little behavioral context — no mention of pagination, date-range scoping, or whether output is grouped, presumably because the annotations already carry the safety profile.

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 purpose and usage, plus a compact API reference for implementers. Nothing is redundant and no sentence is wasted.

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 simple one-param read tool with an annotation covering the safety profile, purpose plus the pre-rostering usage cue is enough to call it correctly. The only mild gap is that with no output schema there is no hint about the shape or volume of returned unavailability entries.

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?

There is a single parameter and schema description coverage is 100%, so the schema already documents employee_id adequately. The description adds no syntax or format detail beyond what the schema provides, which is the expected baseline for a fully covered single-param tool.

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 times one employee ... unavailable to work') and names the scope precisely: one employee's unavailability records. This clearly distinguishes it from the sibling deputy_add_unavailability (which writes) and from shift/timesheet tools.

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?

Gives an explicit usage cue — 'check before rostering them' — which tells the agent when this tool is relevant. It stops short of naming an alternative or stating exclusions, so it is clear context rather than a full when/when-not decision rule.

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