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

Annotations declare destructiveHint=true; the description adds that the default is a DRAFT with no number and that draft=false consumes the next series number — useful behavioral context for a mutation. It does not itself restate the 'cannot be undone' warning (that lives in the schema), so it stops short of full disclosure.

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 front-loaded sentences, each earning its place: purpose, draft semantics, sibling disambiguation, and return/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?

Despite no output schema, the description names the return fields (series, number, documentId, links) and the endpoint, and covers the draft/issue distinction — everything an agent needs to call it correctly given the rich schema.

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%, so baseline is 3. The description restates the draft default and the return fields, adding little meaning beyond what the schema already documents in detail for every parameter.

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?

States a specific verb+resource ('Create a proforma (estimate)') plus scope ('for a client with product/service lines') and explicitly distinguishes itself from a sibling concept by noting 'A proforma is not a fiscal invoice', separating it from smartbill_create_invoice.

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?

Gives clear context on when the draft-vs-issued distinction matters and states the default, but does not explicitly name alternative siblings (e.g. smartbill_create_invoice) or conditions that would route to them. Clear usage without explicit exclusions.

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