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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered. The description adds that the data is the official RF calendar with holidays and transfers, but omits coverage years/freshness and any note on whether the calendar is bundled or remote, so beyond the mode mechanics it contributes modestly.

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-loads the resource statement, then a cleanly numbered three-mode list; every clause carries information an agent needs. The only mild redundancy is the bilingual English restatement at the end, which duplicates the opening rather than adding content.

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 no output schema, the description does describe what each mode returns (a resulting date, a count of days and hours, a day classification plus next working day). It stops short of stating the response shape or the calendar's year coverage, which an agent might need for edge dates outside the supported range.

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 goes further by defining the meaning of parameter combinations rather than individual fields — which pair triggers addition, counting, or classification. It does not restate format details already in the schema, which is appropriate.

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?

Names the specific resource (Russian production calendar with official holidays and transfers) and enumerates exactly what the tool computes in each of its three modes. Sibling tools (amount_in_words, decline_name, validate_requisites) are in unrelated domains, so no disambiguation is needed and none is attempted.

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 maps each parameter combination to a distinct use case: date + add_working_days for deadline arithmetic, date + end_date for day/hour counting, and date alone for weekday/holiday classification. It even frames a real scenario ("оплата в течение 5 рабочих дней"), leaving no inference about when to pick a mode.

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