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 clearly states the authentication requirement and the fact that the call will fail until the account is connected: 'Requires sign-in (OAuth): this session is not authenticated, so calling this tool will fail until the PDFIntact account is connected and authorized.' It also explains the credit unit (1 page = 1 credit) and what will be returned, providing excellent transparency.

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 compact and well-structured. The first sentence states the core purpose and scope, immediately followed by concrete use cases. The second paragraph adds a necessary authentication warning without unnecessary detail. Every sentence earns its place.

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, no-output-schema tool, the description is complete. It tells the agent why to call the tool (before conversion or after an error), what information will be returned (balance, expiring lot, purchase link), and the expected failure if not authenticated. Nothing important is missing.

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 baseline is 4. The description adds useful context about what 'balance' means (1 page = 1 credit) and the authentication prerequisite, though there are no parameter semantics to clarify. This satisfies the baseline for a no-parameter tool.

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 states a specific action ('Check the current PDFIntact credit balance') and resource (credit balance plus soonest-expiring credit lot), making the tool's purpose immediately clear. It is distinguished from sibling tools by its explicit reference to convert_pdf and get_result contexts, so an agent can tell it apart.

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 explicit usage context: 'Useful before submitting a large PDF to convert_pdf, or after an insufficient_credits error...' This tells the agent when to call the tool. It doesn't describe when not to use it or explicitly name alternatives, but for a simple balance lookup with no direct sibling overlap, the guidance is sufficient.

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