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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds real domain context by defining the returned set as invoices 'created but not yet sent to the SDI' and citing the underlying endpoint GET /invoices/draft. It says nothing about result size, ordering, or pagination behavior beyond what the schema already documents.

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 short fragments, front-loaded with the defining state of the resource before the cross-reference and endpoint. Nothing is wasted. Slightly clipped prose (no explicit verb) and the reliance on another tool's documentation keep it from a 5.

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 zero-required-parameter read-only list tool with a fully documented schema and annotations, the description covers the essentials. What it omits is what SDI means for an unfamiliar agent and any note on how the draft set is scoped or ordered — minor, but the description leans on the sibling for filter semantics.

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% — every one of the six filter parameters has its own description, defaults, bounds, and format patterns. The description adds only a cross-reference ('same filters as acube_list_invoices'), which helps an agent transfer expectations but conveys no new per-parameter meaning. Baseline 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 names the exact resource and its distinguishing state: draft invoices created but not yet sent to the SDI. That cleanly separates it from acube_list_invoices (sent) and acube_get_draft_invoice (single record). The verb 'list' comes from the name/title rather than the prose, so it falls just short of a fully self-contained 5.

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?

'Same filters as acube_list_invoices' implies this is the draft-state counterpart to that listing, which is useful context. But it never explicitly says when to pick this over acube_list_invoices or acube_get_draft_invoice, nor any prerequisites (e.g., that drafts are pre-SDI-submission only). Usage is implied rather than stated.

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