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

Beyond the annotations (readOnlyHint, idempotentHint), the description adds that the call is free, consumes neither quota nor rate limit, and can be called freely. It also discloses exactly what is returned (balance, quota, reset time, price list). No contradiction with annotations.

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 description is well-structured with labeled sections (Shows/When/Returns/Cost) and front-loaded with the main purpose. However, it repeats the exact same content in Russian and English, doubling the length without adding informational value for monolingual readers. Still efficient overall.

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 tool with no parameters and no output schema, the description is complete: it explains the return values, usage scenarios, and cost implications. There is no missing information needed for an agent to decide when and how to call it.

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 has zero parameters, and the description explicitly states 'takes no parameters' in both languages. Since there are no parameters to document, the description appropriately confirms this; the baseline of 4 for zero-parameter tools is met.

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 clearly states the tool shows remaining balance, daily quota usage, reset time, and tool prices in credits. The verb 'shows' is specific and the resource is unambiguous. It distinguishes itself from sibling tools (search, fetch, extract) by focusing on account/usage information.

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?

Explicit 'when to use' scenarios are provided: after a rate_limited failure, when the user asks about balance/spending, or before a large batch to check credit sufficiency. It also notes the call is free and does not consume quota, giving clear guidance on safe usage.

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