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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds one genuinely useful behavioral detail — the response includes line items — but says nothing about what happens when the id is unknown or whether totals/payments/status are included.

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?

Eight words, front-loaded with the resource and the retrieval key, and the one payload note ('with line items') appended last. Nothing is wasted.

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?

There is no output schema, so the description is the only signal about return contents, and it discloses only that line items are present. For a simple single-param read with annotations covering safety this is workable, but the agent still cannot anticipate the full invoice shape or not-found behavior.

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 single invoiceId is documented as a GUID with a pattern, so the schema does the heavy lifting. The description's 'by id' merely restates that; 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 (get), resource (sales invoice), and cardinality ('one ... by id'), which implicitly separates it from bokio_list_invoices. It does not name a sibling explicitly, but the retrieval-by-identifier purpose is 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?

'by id' implies you must already have an invoice GUID, which is a usable precondition. However, it never says when to prefer this over bokio_list_invoices or bokio_get_credit_note, and offers no exclusions or fallback guidance.

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