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

Adds substantial context beyond the annotations: the invoice is reported to NAV (tax authority), it is irreversible and only cancellable, email delivery is conditional on send_email, the call reaches other people and requires per-call user confirmation, and it needs the Cotlet API key with app access. This is far more than the openWorld/destructive hints convey.

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?

Front-loaded with the core action, then layers the irreversible/NAV behavior, email conditional, and confirmation requirements in tight sentences. Slightly repetitive in restating the send_email default already in the schema, but overall dense and warranted for a financial write tool.

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?

No output schema exists, yet the description discloses the return values (invoice number plus net, VAT and gross totals), the tax reporting side effect, the irreversibility, and the auth/confirmation requirements. Nothing an agent needs to call it safely is missing.

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 already documents all 11 parameters. The description reiterates the email-default behavior and the item composition, which largely duplicates the schema rather than adding new semantic meaning. Baseline 3 is appropriate.

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+resource ('Issue a new invoice for a buyer with line items, payment method and dates') and names the scope (numbered invoice reported to NAV). It also distinguishes itself from the sibling cancel_invoice by clarifying what happens on correction. An agent can route correctly without opening the 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?

Explicitly routes the agent: deletion is impossible, corrections go through cancel_invoice. It also states the confirmation expectation before each call. It lacks guidance on when a draft/alternative creation path would be preferable, but for this sibling set that gap is minor.

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