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

With no annotations, the description carries the full burden of behavioral disclosure. It usefully reveals that the balance includes kopecks as a string for precision, which is a meaningful output nuance. However, it does not explicitly state that the operation is read-only, has no side effects, or what happens on errors.

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 a single concise sentence that immediately states what the tool returns and the key formatting nuance. Every word earns its place, with no fluff or repetition.

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 zero-parameter read-only balance getter with no output schema, the description gives the essential return information: account balance in rubles with kopecks as a string. It is slightly light on explicit output structure or error/authentication behavior, but the tool's simplicity makes the description largely sufficient.

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, so the schema covers all parameter semantics vacuously. The description does not need to explain parameters, and the baseline of 4 for zero-parameter tools 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?

The description clearly identifies the resource (account balance) and the currency/format (rubles and kopecks as a string). However, it is a noun phrase rather than an explicit action statement like 'Returns...', so it does not fully meet the 5-level bar for a specific verb.

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 description gives no guidance on when to use this tool versus alternatives, and no exclusions or prerequisites. While one can infer it is for checking account balance, the text itself does not say this or mention any sibling tool.

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