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

No annotations are provided, so the description carries the full behavioral burden. It discloses non-obvious behavior: drafts are not committed until invoices_issue, currency/dueDate default from the billing profile, and totals are computed server-side so callers must not supply them. This goes well beyond the schema and helps prevent a serious misuse, though it does not address permissions or return values.

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?

Three purposeful sentences, front-loaded with the core purpose before the caveats. Every sentence adds value: draft state, defaults, and the server-side totals warning. No filler or redundant restatement of the schema.

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 create tool with no annotations and no output schema, the description covers the key state-transition semantics, defaults, and a critical caller-error guard. Combined with the high-coverage schema, an agent has enough to invoke it correctly. A small gap remains around expected return value or error conditions, but the absence of an output schema lowers that burden.

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 89%, so the baseline is 3. The description reinforces important context such as defaulting behavior and warns against sending totals, but most parameter-level semantics (line items, charges, date formats, required contact/company) are already documented in the input schema. It does not significantly compensate for the small uncovered remainder.

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 opens with a specific verb and resource: 'Create a DRAFT invoice.' It further distinguishes itself from siblings by defining the draft state (no number, editable/deletable, nothing committed until invoices_issue). An agent can clearly tell this from invoices_issue, invoices_update_draft, and invoices_send.

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 explicitly names invoices_issue as the commitment step, which signals when this draft-creating tool is appropriate versus the issuing alternative. It also notes that drafts can be edited or deleted freely, implying safe pre-commit usage. It does not explicitly contrast every invoice-related sibling, but the draft semantics provide clear contextual guidance.

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