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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description goes further, disclosing pagination mechanics (1-100 per page, pass next_cursor back as cursor), the server-side filter behavior, and the auth requirement (Cotlet API key with app access).

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 lead sentence is well front-loaded with fields and ordering, but 'newest first' is stated twice in the first two sentences and the field list partially duplicates the schema. Every sentence earns its place except the redundancy.

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 carries the burden of describing return values, and it does list the returned fields including remaining_amount_with_tax. Combined with pagination and auth notes, it is nearly complete, though it doesn't describe the response envelope shape.

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%, so the schema already documents every parameter and the status enum. The description restates the status values and the cursor round-trip, adding marginal value but no syntax or format detail beyond the schema; 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 ('Lists customer invoices'), enumerates the returned fields (number, customer, amounts, status, due date), and fixes the sort order (newest first). An agent can distinguish it from pennylane_list_supplier_invoices or pennylane_get_customer_invoice without opening a schema.

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?

Explains the key operational context that Pennylane's native list cannot filter by status or due date and that Cotlet applies the status filter on the agent's behalf. It does not explicitly say when to prefer this over get_customer_invoice, but for a list tool the usage scope is clear enough.

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