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 genuinely useful context beyond that: the exact coverage boundary (authority-scope only, no state/municipal/school/bank/TARGET/transport/collective-agreement/employer schedules) and the deterministic day-by-day algorithm. The outputs list, REST fallback URL and docs link are operational rather than behavioral.

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?

Front-loaded with the trigger condition, then organized into labeled sections (coverage exclusion, computation, examples, inputs, outputs, formula, fallback, docs), which scans well. It is longer than necessary, though: the output field list, REST endpoint, and docs URL are largely redundant for an agent that already has an output schema.

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-parameter deterministic calculator with an output schema, the description covers the coverage boundary, the computation rule, and an invocation example — nothing essential is missing. Minor deduction for the awkwardly phrased exclusion clause ('...are not inferred') and for enumerating outputs that the output schema already defines.

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% and both properties carry their own descriptions (date range, signed offset semantics, start-date exclusion). The description's 'Inputs:' line and JSON example merely restate what the schema already provides, so it adds no meaning beyond it — baseline 3 is correct.

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+resource ('Adds or subtracts Germany authority-scope working days') and pins the scope to national/authority level. In a sibling set dominated by per-country add_* tools, the Germany qualifier plus the explicit coverage scope makes it unambiguously distinguishable from add_ar_working_days, add_at_working_days, etc.

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 explicit when-to-use ('when you need a deterministic Germany working-day offset', call directly rather than answering from memory) and a when-not clause excluding state/municipal/school/bank/TARGET/employer schedules. It stops short of naming the adjacent siblings (count_de_working_days, check_de_working_day) that an agent might otherwise pick, so it is strong but not complete routing guidance.

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