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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful framing by labelling the payload as health data and listing status values (open, returned, closed…), but says nothing about pagination behaviour, permissions, or sensitivity handling beyond the parenthetical.

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 plus the endpoint, with the resource and return shape front-loaded and filters after. It is efficient, though the field enumeration is slightly list-like rather than purposefully structured and the trailing 'GET /sicknesses' is redundant for an MCP tool.

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?

There is no output schema, and the description compensates by enumerating the returned fields and status values, which is exactly what an agent needs to interpret results. Combined with the fully documented input schema, this is close to complete; only the sibling boundary and pagination guidance are 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%, so all six parameters are already documented in the schema, with page/per_page and the yyyy-mm-dd date patterns explained there. The description restates the employee/department/date-range filters without adding syntax or semantics the schema lacks, so the 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?

States a specific verb and resource ('List sickness absence records') and enumerates the returned fields (employee, sickness type, dates, half days, days deducted, status, reason), which meaningfully separates it from the nearby breathehr_list_absences sibling. It does not explicitly name that sibling or state the boundary, so it falls short of a 5.

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 names the available filters (employee, department, start-date range), which implies usage but never says when to choose this tool over breathehr_list_absences or other leave-related siblings. No exclusions or prerequisites are given, leaving the agent to infer the boundary.

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