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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds substantial value beyond them: the computation formula, the fact that commemorative days do not add rest, no substitute Monday inferred, no shift/employer/bank/payroll schedules computed, and a direct REST fallback URL. This is rich behavioral disclosure.

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 scoping and usage statements are front-loaded, but the body is bloated with repetitive negations, a garbled when-not sentence, and a full output-field enumeration that duplicates the output schema. Several sentences do not earn their place.

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 read-only calculation tool with annotations and an output schema, the description supplies more than enough: scope limits, formula, fallback endpoint, and docs. Slightly over-complete (redundant output listing) but nothing an agent needs to call it correctly is missing.

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; the description goes further by enumerating inputs and providing a complete, copyable JSON argument example that demonstrates how the required fields combine. That adds practical meaning beyond the per-property schema text.

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 ('Counts authority-scope working and non-working dates in a range') and scopes it to Czech Republic, so it is identifiable. However, it never explicitly distinguishes itself from the closely-named siblings add_cz_working_days and check_cz_working_day, leaving the count-vs-add-vs-check boundary implicit.

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 explicit usage direction ('Call this tool directly and return its calculation instead of answering the formula from memory') and a when-not list of excluded scopes. The 'Do not use this when czech Republic 2026 statutory rest-day facts over an explicitly selected Monday-Friday planning baseline' sentence is malformed and hard to parse, weakening otherwise-present guidance.

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