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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so safety is covered structurally. The description adds useful behavioral context the annotations lack: no output schema exists, so it enumerates the returned account/scope/counter/credit fields and frames the call as a pre-flight quota check. It still says nothing about freshness, caching, or error behavior when a key is invalid or expired.

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?

Content is front-loaded with the return payload followed by the usage directive, which is the right order. However, the single run-on sentence enumerates fields at length and contains an internal inconsistency: it says 'all five counters' and then lists six items (разборы, правки, отслеживаемые авторы, отчёты, сборки досье, вопросы к корпусу), which weakens an otherwise factual enumeration.

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 carries the burden of describing returns, and it does so field-by-field across both the counter set and the v2 credit block. For a zero-parameter readonly tool this is close to sufficient, with only freshness/validity behavior left unstated.

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, so there is no schema semantics to compensate for and the baseline of 4 applies. The description correctly implies the tool is parameterless by scoping output to the calling key rather than to any supplied identity.

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 concrete resources: the key owner's plan, the key's scopes, and remaining quota across named counters, plus v2 credit fields (remaining, period, daily cap, action prices). An agent can tell this is a quota/entitlement lookup rather than a data query. It does not, however, distinguish itself from overlapping siblings such as account, my_profile, or credit_history.

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?

The closing sentence gives an explicit rule: call this BEFORE any operation that spends quota, because the response shows whether it is worth starting. That is clear contextual guidance with a stated rationale. It stops short of naming the sibling alternatives (credit_history, account) or stating when not to call it.

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