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

The description adds substantial behavioral context beyond the annotations: it specifies what is copied (client, lines, tax, notes, terms), that the draft is dated today, has no number until sent, creates no work or payments, and counts toward the free plan limit. However, it does not address the destructiveHint: true annotation, which could confuse an agent expecting a destructive operation; the description implies a purely additive creation.

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 front-loaded with the core action and packs all necessary details into two compact clauses. Every phrase adds value, and there is no redundant or filler text.

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 tool with no output schema, the description covers the essential behavior, creation details, and a notable side effect (free plan limit). It could be slightly more complete by explicitly stating that the original invoice/estimate remains unchanged, but it is largely sufficient.

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% and the sole parameter invoiceId is already documented as 'The invoice or estimate.' The description reinforces this by referencing 'an invoice or estimate', but adds no new meaning beyond the schema, so the baseline of 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?

The description states a specific verb ('Creates a new draft') and resource ('with the same client, lines, tax, notes and terms as an invoice or estimate'), clearly distinguishing it from sibling tools like create_invoice or convert_estimate_to_invoice. An agent can immediately tell this is for duplicating an existing document.

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?

The description implies when to use it (to copy an invoice or estimate) but does not explicitly say when to choose this over alternatives like create_invoice or create_invoice_from_work. No exclusions or alternatives are named, leaving the agent to infer the appropriate context.

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