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

With no annotations, the description carries the full behavioral burden. It discloses the important semantic that each item may carry independently set prices per currency rather than converted values, but it omits pagination, ordering, filtering, and response shape. This is useful but incomplete.

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?

The description is two sentences, front-loaded with the core action, and the second sentence earns its place by explaining a non-obvious pricing behavior with a concrete example. No wasted words.

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 parameterless list tool, this is largely complete: it states the resource and the key data behavior. It lacks explicit mention of pagination or exact return fields, but those are minor given no parameters and no output schema.

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?

The tool has zero parameters, so the description cannot meaningfully add parameter semantics beyond the schema; the baseline 4 applies. It does clarify the data model that the returned fields represent.

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?

The description clearly names the operation ('List') and the resource ('reusable invoice items') and adds a distinctive detail—per-currency prices—that separates it from invoice_items_create/update and invoices_list. Even without looking at the schema, an agent knows exactly what this tool returns.

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?

It provides clear context that this is the read-only retrieval tool for reusable invoice items and explains the per-currency pricing model, so an agent can identify when it is relevant. It does not explicitly state exclusions or alternatives, but the sibling pairs (create/update/list) make the usage obvious.

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