Retrieve a debit invoice

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

With no annotations, the description carries the full burden and does so thoroughly. It discloses read-only nature, source of PDF URL ('from the document's own Links'), and the special handling of credit notes. No contradictions.

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?

Four concise sentences, front-loaded with the core function, then details. Every sentence adds value (scope, identification rules, differentiation, edge-case behavior) 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 retrieval tool with no output schema and no annotations, this description is complete: it specifies what is returned (detail, PDF URL), how to identify the invoice, and what happens on mismatch. Nothing essential 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?

Schema coverage is 100%, so baseline is 3. The description adds the mutual-exclusivity constraint ('pass one, not both') and clarifies that full_number is as printed with an example. This is valuable beyond the schema, though the schema already documents the parameters well.

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?

States a specific verb+resource ('Retrieves one ProAbono debit invoice') and enumerates the included details (status, amounts, dates, payment method, note, PDF URL). It also differentiates itself from get_credit_note explicitly, making its scope unambiguous.

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?

Provides explicit guidance: 'pass one, not both' for the two identifiers, and names the alternative tool (get_credit_note) for credit notes. It also explains behavior when the identifier resolves to a credit note, giving clear conditions for use.

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