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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false) by disclosing downstream state effects (invoice leaves open/overdue lists), reversibility (delete via trash icon), a role restriction ('Belege, Kontakte & Produkte' users cannot delete payments), the per-call confirmation workflow, and the auth requirement.

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?

Purpose is front-loaded and most sentences carry real information (state effect, reversibility, permissions, confirmation, auth). Minor padding from UI-click and trash-icon detail keeps it from being maximally tight.

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 mutation tool with no output schema, the description supplies the missing behavioral burden: consequences, reversibility, permission limits, confirmation need, and auth. Only sibling routing is absent, which is a minor gap.

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 amount, payment_date, payment_type, and document_id are fully documented in the schema itself. The description only restates these fields without adding format or syntax meaning, so baseline 3 applies.

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 and resource ('Record a customer payment on an open invoice'), plus the exact mechanism (Zahlung erfassen on the invoice). This is clearly distinguishable from sibling read tools like list_documents or list_receipts at a glance.

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 operating context: applies to an open invoice, requires user confirmation before each call, and needs an API key with app access. It does not name sibling alternatives (e.g. send_payment_reminder vs recording a payment), so it stops short of explicit when-not guidance.

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