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

Annotations already declare idempotentHint=false and destructiveHint=false, but the description converts that into an actionable consequence: calling twice creates two drafts. It also clarifies the draft is inert until sent, which goes beyond the annotation set. It omits permissions/auth requirements and error behavior, so not a 5.

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?

Four short sentences, front-loaded with the WRITE marker, each carrying distinct information (draft semantics, non-idempotency, validation prerequisite, endpoint). No filler.

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?

Covers the mutation semantics, duplication risk, and pipeline position for a nested-body tool with no annotations gap. The remaining gap is the return shape: with no output schema, the description never says the response yields the draft identifier an agent would need for acube_send_draft_invoice.

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% and the nested field guidance (dati_generali, dati_beni_servizi, full header with seller and buyer) lives in the schema itself. The description adds no parameter-level detail beyond naming the endpoint, so the baseline 3 applies.

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?

Opens with a specific verb and resource plus scope: 'WRITE: saves a new invoice as a DRAFT in A-Cube.' It also distinguishes itself from the send path by name (acube_send_draft_invoice), so an agent can tell create-draft from send-draft without opening either 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?

Explicit sequencing: validate first with acube_validate_invoice, nothing reaches the SDI until acube_send_draft_invoice. It names the prerequisite and the follow-up tool, which is exactly the when/when-next guidance an agent needs.

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