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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: by default it returns a stored (potentially stale) status, and refresh=true performs a live round-trip to FACe. What it does not mention is failure behavior when FACe is unreachable or the invoice has no FACe record.

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?

Two tight sentences: the first front-loads the resource and its value set, the second carries the one behavioral switch. Nothing is repeated from the schema or title.

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?

With no output schema, the description compensates well by enumerating the returned status values and noting that cancellation-request state is included. The remaining gap is the identity/format of invoice_id and what happens on FACe lookup failure.

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 coverage is 50%: refresh is documented in the schema, invoice_id is not. The description fully explains refresh's live-vs-stored semantics and default, which is useful, but invoice_id — whether it is the internal invoice ID or a FACe registry number — is left undocumented in both places.

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 resource and scope: the FACe processing status of an invoice, and enumerates the six possible states. The FACe/B2G framing separates it from generic invoice readers like get_invoice, though no sibling is named explicitly.

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?

Usage is implied by the purpose (check FACe submission/cancellation state), and the description does explain when to set refresh=true versus leaving it false. It never says when to prefer this over get_invoice or what to do if the invoice was never submitted to FACe.

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