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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so safety is covered. The description adds genuine behavioral context beyond that: it is deterministic, assigns no compensation date or next-Monday closure, excludes bank-only Good Friday/Christmas Eve afternoon, and covers only the Monday-Friday planning baseline rather than a personal roster. It does not discuss performance or failure modes, 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?

The description is heavily padded and repetitive: the same scope caveats (no compensatory leave, no bank-only closures, no personal roster) are restated three times, the opening is ungrammatical, and inputs/outputs/formula/docs are enumerated at length even though an output schema exists. The one useful routing sentence is buried mid-block.

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 2-param, read-only lookup with an output schema, the description covers the necessary scope limits: coverage window (2026-2028), weekend-plus-statutory-holiday baseline, and everything deliberately not computed. The REST fallback and doc links are supplied. Listing output fields is redundant given the output schema, but nothing an agent needs to call it correctly is absent.

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 the baseline is 3. The description reinforces that work_schedule must be an explicit mon_fri_planning baseline and that it is not a personal roster, but adds no syntax or format detail beyond the schema for either parameter.

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 opening sentence is garbled ("a deterministic Luxembourg Luxembourg 2026-2028 eleven annual statutory holidays with explicit Monday-Friday planning baseline before individualized leave result"), which obscures the purpose. However, the later line "What it computes: Checks a date against the Saturday-Sunday weekend baseline and exact 2026-2028 authority events" does state a concrete verb+resource+scope. It distinguishes the statutory-baseline scope from personal leave, but never names sibling check/count/add tools directly.

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?

It explicitly frames usage with "Use this when..." and a "Do not use this when..." boundary, plus repeated exclusions (no compensatory date, no next-Monday closure, no bank-only holidays, no personal roster). The negative guidance is garbled and largely restates the positive case rather than pointing to an alternative tool, so it stops 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.