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

Adds substantial context beyond annotations: the PAYMENT-stage trigger on signed provider events, the platform fee of CHF 0.10 per accepted call, and the required quote_id/mandate_token/idempotency_key sequence. These are non-obvious operational facts that annotations cannot express.

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 dense sentences, front-loaded with the action and scope, then constraints, then cost. No filler, though the final sentence packs fee and parameter list tightly and could read as run-on.

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 money-moving mutation with no output schema, it covers preconditions, safety exclusion, fee, and idempotency. It does not state what the response contains or where the quote must come from, but otherwise complete for reliable invocation.

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 80% and already documents flow_id, quote_id, mandate_token, and idempotency_key with patterns. The description reinforces the required send order and mentions mandate_token/idempotency_key, but adds no syntax beyond the schema. Baseline 3 holds when the schema is near-complete.

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 (creates) and resource (payment request for the invoice) and enumerates supported methods (QR bill, TWINT, card). Distinguishes from siblings like invoice_issue and mandate_create by naming the PAYMENT flow stage and required INVOICE state.

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 preconditions (needs state INVOICE, signed event from payment provider) and an explicit exclusion ('Never: Mark anything paid or pay out without a settled status'). Also names the quote-then-send sequence. No direct sibling routing, but conditions are clear.

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