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

Annotations only cover mutability/idempotence/destruction flags, so the description carries the burden of behavioral context. It adds a useful fact: beneficiary IBAN and name default to the shared business profile and are never asked for. It does not discuss output behavior, file creation, authentication needs, or side effects, though those are partially hinted at in the schema.

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 sentences with no filler. The usage condition is front-loaded, and the default-beneficiary behavior is stated in the second sentence. Every phrase earns its place.

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 14-parameter tool with no output schema, the description plus schema is mostly sufficient, and the shared-profile context is valuable. However, the description does not describe the return contract (inline SVG versus downloadable PNG) and does not clarify how this tool relates to invoice_payment_qr; the agent must infer these from the out_path parameter and sibling names.

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 100%, so the baseline is 3. The description earns extra credit by emphasizing the minimal viable payload ('Amount and reference are enough') and clarifying that beneficiary data is supplied by defaults rather than required input. This helps an agent assemble a valid call without opening every schema field.

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 action ('Call this tool for an EPC069-12 payment QR') and names a concrete output (a QR a euro banking app can scan). It is clearly distinguished from barcode, wifi, and vcard QR tools, though it never explicitly names or separates itself from the close sibling invoice_payment_qr.

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 gives an explicit trigger condition: use this for an EPC069-12 SEPA payment QR. It also gives practical guidance that amount and reference are enough, and that beneficiary IBAN/name come from the shared profile. It does not name alternatives or state when not to use it, so it stops short of a 5.

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