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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context the annotations cannot: the holiday rules are versioned 'as of 2026-08-15', which tells the agent how current the legal basis is. It does not describe the shape of the result (e.g. whether the returned end date is inclusive), which keeps it below 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?

Purpose, modes, and the sibling exclusion are front-loaded in the first two sentences, with examples relegated to the end where they belong. The five German example questions are helpful for matching but make the block longer than strictly necessary for an agent.

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 7 parameters and no output schema, the description covers the important ground: both modes, the state-specific holiday basis, the rules version, and the scope boundary. What is missing is any statement about the returned value (e.g. the resulting date or day count, or which parameters are required per mode), which matters for a tool with mode-dependent inputs.

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 meaning beyond the raw enum: it explains that 'land' selects that state's public-holiday calendar, which is the key semantic link between the parameter and the computation. The mode split (add vs count) is also framed in prose. The samstag flag and the date-format tolerance of 'start' are left entirely to 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?

States a specific verb and resource (count working days between dates / add working days to a start date) plus the scope of 16 German federal states with their public holidays. It explicitly names the two modes and distinguishes itself from calculate_tender_deadline, so an agent can identify it without opening the schema.

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 intake criteria ('Intended for requests where the user asks how many working days lie between two dates or which date is n working days after a start date') plus a clear exclusion routing procurement-law deadlines to calculate_tender_deadline. Concrete example user questions further pin down the trigger cases.

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