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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description earns credit for disclosing the return shape – all fields plus line items – which the agent needs to know before deciding to call it, though it says nothing about error behavior for missing ids.

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 sentences, zero filler, with the primary behavior stated first and the invocation hint second. 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?

With a single fully documented parameter, readOnly annotations, and no output schema, the description covers what an agent needs. The only soft gap is no guidance on how non-numeric identifiers other than code: behave, which the schema only gestures at.

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%, and the schema already enumerates the identifier prefixes and pattern. The description restates 'numeric id' and 'code:<number>' but adds no meaning beyond the schema, so the baseline 3 applies.

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 and resource: retrieve one issued invoice, including all fields and line items. The word 'one' implicitly contrasts with the list variants, and '(from the list)' points at the sibling source, so an agent can separate it from list_issued_invoices without opening a schema, though the sibling is never named.

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 a partial routing hint by saying the numeric id comes 'from the list', which tells the agent to enumerate first. It does not explicitly name the list tool, state when not to use this one, or contrast it with abraflexi_get_record.

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