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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the mutation profile and closed-world scope are covered by structured data. The description's only added behavioral signal is the word 'draft', which implies a non-finalized record that can later be edited or submitted, but it does not state side effects, whether anything is posted to the ledger, or whether the call is idempotent.

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?

It is a single sentence with no filler and the verb-resource pair is front-loaded, which is appropriate for a one-parameter tool. The brevity tips into under-specification, but no sentence is wasted.

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 simple one-required-parameter create with full schema coverage and no output schema, minimal prose is defensible. Missing context is the shape of the created draft (line items, dates, amounts, defaults), whether it is immediately editable, and how it relates to submit-invoice, all of which the agent would need to know to proceed after the call.

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% for the single companyId parameter, so the schema already carries the parameter documentation and the baseline of 3 applies. The description adds nothing about the parameter, leaving any format or lookup requirements entirely to the schema.

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 names a specific verb and resource ('Create a draft invoice') and scopes it to a company, so an agent knows what it produces. It does not, however, distinguish itself from close siblings such as submit-invoice, update-invoice-draft, duplicate-invoice, or create-credit-note, so the 'draft' vs 'submitted' boundary is left implicit.

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?

There is no explicit when-to-use guidance, no mention of prerequisites (companyId must reference an existing company), and no routing to alternatives. The natural workflow (create draft, then update-invoice-draft, then submit-invoice) is never stated, so the agent must infer it from sibling names.

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