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

Annotations already declare read-only, idempotent, non-destructive and closed-world behavior. The description adds scope ('Demo invoicing') and a usage context, but does not disclose auth needs, rate limits, or side effects beyond what annotations and the output schema already provide.

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?

Three short sentences, front-loaded with what the tool returns, followed by usage and environment scope. Every sentence contributes without 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?

Given the rich annotations, output schema, and simple retrieval nature, the description is nearly complete. The main gap is the lack of any mention of the optional account parameter, though the schema itself describes 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?

Schema description coverage is 50%; the description compensates by naming series and number and by covering the invoice/proforma distinction (doc_type), but it omits the optional account parameter and adds no format or constraint detail for series/number.

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 retrieval action and resource: 'One invoice or proforma by series and number', with a clear scope of returned fields. It distinguishes itself from list-style siblings by implying a single document, though it does not name an alternative tool explicitly.

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?

It gives a clear use case: 'Use it to check a document after issuing or cancelling it.' There are no explicit when-not conditions or named alternatives, but the context is sufficient for selecting it over invoices_list.

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