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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds real behavioral context beyond them: deterministic computation, a pinned holiday package with a bounded 2026-2027 coverage, conservative skipping of published half-days, and an explicit formula. It omits auth/rate-limit notes, keeping it just short of 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?

Content is sectioned and front-loaded with the decision ('Use this when... / Do not use this when...'), and the formula and REST fallback are genuinely useful. The full enumeration of ~18 output fields duplicates the existing output schema and is the one wasteful 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 two-parameter deterministic calculator with an output schema and full annotation coverage, everything an agent needs is present: scope, coverage window, an exact call example, computation formula, and a REST fallback path. No material gap remains.

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 start_date and working_days are already fully documented (including the signed-offset and exclusion semantics). The description only restates the parameter types and repeats an example that the schema already carries, adding no new meaning.

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 ('Adds or subtracts dates using Türkiye's pinned statutory public-holiday package') and pins the jurisdiction and coverage window (2026-2027). This cleanly separates it from the ~60 territory siblings (add_de_working_days, add_ar_working_days, etc.) and from count_/check_ variants.

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?

Explicitly says when to use it ('deterministic Türkiye statutory working-day offset in 2026-2027'), instructs the agent to call rather than answer from memory, and gives a when-not clause ('employer or sector calendar, or the date falls outside the pinned coverage'). Routing intent is unambiguous.

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