Get one invoice

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

With no annotations provided, the description carries the full burden, and it does well by disclosing not just that it returns a record but also the nested richness of that record, including the unusual credit-note-adjusted open balance. It does not discuss error cases or permissions, but the read-only nature is clear from 'Return'.

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 front-loaded sentence that efficiently conveys the core purpose and key return-value details. The parenthetical '(see credited_minor)' is somewhat cryptic and unexplained, slightly reducing clarity, but overall there is no wasted wording.

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 simple single-parameter get operation with no output schema, the description covers the essential information an agent needs: what it returns, the scope ('one invoice number'), and notable computed fields. It could be more complete with explicit not-found behavior, but the core call context is adequately covered.

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 schema only documents 'number' as a string with zero description coverage. The tool description adds that it identifies the invoice, which is minimal but useful; it does not specify format, uniqueness requirements, or how to discover valid invoice numbers.

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') with a clear resource ('the full stored record for one invoice number'), making the tool's purpose unmistakable. It also highlights distinctive content (line items, tax breakdown, credit-note-adjusted balance) that separates it from siblings like invoice_summary or invoice_list.

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 when to use the tool: when you have an invoice number and need the full record rather than a summary. However, it does not explicitly contrast it with alternatives such as invoice_summary, invoice_list, or invoice_pdf, leaving routing decisions partly to inference.

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