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

Annotations already cover the read-only, non-destructive, open-world profile, but the description adds substantive traits beyond them: no per-employee filter, no paging, and results must be read per user, which materially affects invocation strategy. It also names the underlying GraphQL query (timeOffBalances), useful for debugging. It doesn't discuss result volume or ordering guarantees, so not a 5.

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?

Three sentences, front-loaded with what the tool returns and followed by filtering and API constraints; no filler. Slightly dense enumeration but every clause carries information.

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 compensates by itemizing the returned fields, and the no-paging/no-per-employee-filter caveat closes the biggest behavioral gap. What's missing is minor: sorting behavior and rough result-size expectations.

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 83%, so the schema already documents nearly every parameter with meaning, formats and cross-references (e.g. time_off_type_id from kiwihr_list_time_off_types). The description only restates the filter categories and says nothing about the sort_by/sort_direction parameters, adding little beyond the schema.

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 uses a specific verb and resource ('Time off balances of all employees') and enumerates the returned fields (allowance, accrued, used, requested, planned, available, carry-over, periods), so an agent knows exactly what comes back. It does not explicitly differentiate itself from close siblings like kiwihr_get_time_off_usage or kiwihr_list_overtime_balances, which keeps it from 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?

'Filter by time off type, active state and usage period' plus 'The API has no per-employee filter or paging for this query; read the result per user' gives concrete, actionable usage context, including an important constraint that shapes how the agent should call it. There is no explicit when-to-use-versus-sibling routing, so it falls short of a 5.

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