Справочное дерево регионов

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the result is large and stable and should be cached rather than re-fetched. Minor gap is that it does not say anything about the tree's depth or whether pagination applies, though with no parameters pagination is unlikely.

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?

Three tight sentences: identity of the resource first, then how to use the output, then the caching hint. Every sentence carries information and nothing is repeated from the schema or annotations.

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 input schema fields to explain and no output schema, the description carries the return-value burden and does it reasonably: ids plus labels, large and stable. It stops short of describing the tree's structural shape (nesting/parent-child) or example values, which would fully close the gap for an agent parsing the response.

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?

The tool takes zero parameters, which is the baseline-4 case. The description correctly implies no inputs are needed and instead explains how the output feeds sibling tools' parameters, which is the only parameter-adjacent meaning available.

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 names a specific verb and resource ('Возвращает справочное дерево регионов') and states exactly what the payload contains: region ids and their labels. It also implicitly separates this reference lookup from the sibling `regions`, which computes statistics, by framing this tool as a lookup table that feeds the other tools' parameters.

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 tells the agent precisely where the returned ids go ('подставляются в regionIds/regionMode остальных инструментов') and what the labels are for (decoding ids in other tools' responses). It also advises calling once and caching because the tree is large and stable. No explicit 'do not use this for X' exclusion is given, which keeps it just short of a 5.

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