Get page-credit balance

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

Annotations already declare readOnlyHint=true and openWorldHint=true, indicating a read-only, externally mutable resource. The description adds clarity by specifying the exact credits (total, reserved, available) and confirming the unit (PDF pages). No contradictions found.

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?

Two short, dense sentences with no wasted words. The first sentence states what the tool returns, the second clarifies the measurement unit. Perfectly front-loaded and efficient.

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 tool with an output schema, the description fully covers the purpose, items returned, and units. The output schema presumably details the structure, so no additional return-value explanation is needed.

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?

Schema description coverage is 100%, and there are no parameters to document. The description provides the meaning of the return values (total, reserved, available) which is helpful, but since there are no params, a baseline of 3 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 uses a specific verb ('Return') and identifies the resource ('MainBook credits') and three precise items (total, reserved, available). It distinguishes itself from siblings like 'convert_bank_statement' or 'list_conversions' by being clearly a balance/account query tool.

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 implies use when an agent needs to check credit balances before performing PDF-related operations. It does not explicitly state when not to use it or name alternatives, but with 0 params and a dedicated name, its niche is obvious.

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