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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: commemorative days do not create rest, no substitute Monday is inferred, future-year coverage is not asserted, and the exact formula and REST fallback path are disclosed. This is well past the reduced annotation bar.

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?

It front-loads the core purpose well, but the body is bloated and repetitive, with garbled fragments like 'around Two names on January 1, one rest date' and 'in 2026-2026.' Several sentences restate the same coverage exclusions, diluting the signal.

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?

An output schema exists and annotations cover the safety profile, so the description needn't explain returns, yet it still lists them. It thoroughly covers the policy scope and constraints an agent needs, though the garbled example phrasing leaves minor ambiguity about the intended use cases.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it supplies a complete JSON argument example, the planning_workday formula, and clarifies that work_schedule is an 'explicit Monday-Friday planning baseline, not a statutory universal roster.' That goes beyond what the schema fields state on their own.

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 states a specific verb+resource: 'Adds or subtracts Czech Republic authority-scope working days in exact coverage.' It is clearly the add variant within the add_/check_/count_ family, so an agent can distinguish it from sibling tools. It stops short of naming the alternative tools explicitly, so it lands at 4 rather than 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?

It gives genuine usage direction: 'Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery,' and it enumerates what it does NOT cover (shift, employer, bank/exchange, school, retail, payroll, legal-deadline schedules). The 'Do not use this when...' sentence is grammatically broken and hard to parse, which weakens an otherwise strong routing statement.

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