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

readOnlyHint=true already declares the safety profile, so the bar is lower; the description still adds the REST endpoint (GET /settings/payment-method/) and explains the semantics of the returned type codes (1 bank transfer, 2 cash, 4 cash on delivery, 8 card). It does not state whether the type list is exhaustive (trailing '...' implies more codes exist) or mention pagination/empty-list behavior.

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 compact sentences that front-load the returned structure and end with the actionable id-usage hint and endpoint. The enum expansion is dense but useful; the trailing 'GET /settings/payment-method/.' is the only mildly extraneous element.

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 carries the burden of describing returns and does so for the key fields (id, name, type) plus the enum mapping, which is the minimum an agent needs to pick a payment method id. The incomplete enum ('...') and absence of ordering/empty-state notes are the only gaps for a simple zero-param list tool.

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?

The tool takes zero parameters, so the baseline is 4; the empty input schema is consistent with the description, which implies an account-scoped listing with no filtering inputs.

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 names the resource precisely ('The payment methods of the account') and enumerates the returned fields (id_payment_method, name, type) with the type enum mapping, so an agent knows exactly what comes back. It is clearly distinct from sibling list tools such as list_tags or list_number_series, though it never states the verb 'list' explicitly and leans on the title for that.

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?

It gives explicit downstream guidance: 'Use the id in vyfakturuj_create_invoice', which tells the agent why and when this call matters in the workflow. It does not name any alternative or exclusion condition, but for a unique read-only settings lookup there is no competing sibling to route away from.

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