Account balance

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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds meaningful behavior: it returns two distinct balance fields in rubles, is a point-in-time snapshot, and does not perform any top-up action. No contradictions 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 three sentences, front-loaded with the primary purpose, then details about the return value and limitations. Every sentence contributes value with no redundancy.

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 no-parameter, read-only tool with no output schema, the description fully covers what the agent needs to know: what is returned, the units, the distinction between real and bonus balance, and the fact that it is not a historical or funding operation. Sibling tools and annotations complement without gaps.

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 input schema has zero parameters, and the description explicitly states 'Takes no arguments', making it clear to the agent that no input is needed. This adds direct confirmation beyond the schema.

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 precisely states the verb 'Returns', the resource 'current balance of the configured ad account', and the exact return fields (balance and bonusBalance in rubles). It distinguishes this tool from statistics tools by clarifying it is not a history, and from account management tools by noting it does not top up.

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 says 'Takes no arguments' and gives a clear use case: a snapshot of right now, not history. It directs users needing historical spending to use the statistics tools. Also clarifies that it does not top up the account, steering away from misuse.

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