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

The readOnlyHint annotation already establishes this is a safe read, so the bar is lower. The description adds the underlying endpoint mapping (GET /Invoice/{invoiceId}/getPositions), which is genuine backend context, but says nothing about pagination behavior, result caps, or default ordering — all relevant since limit/offset exist.

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?

A single tightly written sentence that front-loads the verb and resource, defines the domain term, and ends with the endpoint reference. Every clause earns its place; nothing is padded.

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 read-only list endpoint with no output schema, the description usefully sketches the returned fields and the exact API path, and the input schema is fully self-documenting. It is only short of complete because paging behavior and the relationship to sevdesk_get_invoice are left unstated.

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%, so the schema fully documents invoice_id, embed, limit, and offset, and the baseline is 3. The description adds no parameter-level meaning — it lists returned fields rather than inputs — so it neither compensates nor detracts.

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 — 'List the positions (line items) of one invoice' — and disambiguates the jargon 'positions' with the plain-language 'line items'. It also enumerates the payload shape (name, quantity, price, tax rate, sums), which separates it from the sibling sevdesk_get_invoice that returns the invoice itself, though it never names that sibling explicitly.

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?

Usage is only implied by the scope phrase 'of one invoice' and the required invoice_id. There is no statement of when to prefer this over sevdesk_get_invoice, no prerequisite that the invoice must already exist, and no guidance on paging via limit/offset despite those parameters being present.

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