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 only the underlying endpoint (GET /finance/purchaseInvoices/{id}) and the fact that line items are included in the response; it says nothing about pagination, error behavior, or permissions, but with annotations in place that is not a major gap.

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 short sentences with the purpose front-loaded; nothing is bloated. The second sentence, the raw API path, is supplemental mapping information rather than description of the tool's own behavior, keeping it just short of a 5.

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 one required parameter fully documented in schema, readOnly annotations, and no output schema, the description is nearly sufficient; the mention of line items covers the return shape at a high level. An agent could call it correctly with no further information, though return-field detail and id-format expectations are absent.

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 100% for the single 'id' parameter, so the schema already documents it. The description only restates that the id goes in the path; it adds no format guidance (e.g., numeric vs string id conventions allowed by the anyOf schema).

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: 'Get one purchase invoice', and adds scope detail ('with its line items') that says what comes back. It does not name the sibling kledo_list_purchase_invoices or otherwise explicitly distinguish itself from the list variant, so it falls short of a 5.

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 singular 'Get one' implies retrieval of a single record by id, but there is no explicit statement of when to use this vs kledo_list_purchase_invoices or the sibling kledo_get_invoice. No prerequisites or failure conditions (e.g., unknown id) are mentioned.

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