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

Goes well beyond destructiveHint=true: states irreversibility, the cascade to line items and PDFs, the exact rejection conditions (linked email, reminder, payment, credit note; finalized invoices are cancelled via credit note instead), and that the import credit is not refunded. Adds that no email is sent, closing a common side-effect question.

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-loads the action and cascade, then consequences, then eligibility rules — every sentence carries distinct information. It is dense but slightly long; the 'does not email anyone' line is a useful but minor addendum.

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 single-parameter destructive tool with no output schema, an agent has everything needed: what is destroyed, what blocks deletion, what happens to finalized invoices, and that the operation is irreversible.

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?

Only one parameter, 'id', already fully documented in the schema at 100% coverage. The description adds no format, sourcing, or lookup guidance for the ID, so it neither helps nor harms beyond the schema baseline.

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 (permanently deletes one invoice) plus the cascade scope (line items, uploaded PDFs). This is immediately distinguishable from sibling mutators like update_invoice or delete_customer.

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?

Gives explicit when-to-use cases (a draft the user no longer wants, an unused import) and precise preconditions for rejection. It does not name sibling alternatives such as update_invoice or a cancellation path, but the usage conditions are unambiguous.

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