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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds the auth requirement (a Cotlet API key with access to this app) and the anti-double-booking rationale for include_invoices, which is genuine context. It does not describe pagination behavior or result shape, so it adds moderate but not rich value.

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?

Four short sentences, front-loaded with the resource and the key optional parameter's purpose. Slight redundancy between the first two sentences keeps it from a 5, but nothing is wasted.

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 two-optional-parameter read tool with no output schema, the description covers purpose, the meaningful parameter's intent, and the auth requirement. It does not explain return fields, but with readOnly annotations and full schema coverage nothing essential to correct invocation is missing.

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 would be 3. The description goes beyond the schema for include_invoices by giving the reason to use it ('so a transfer is not booked twice'), which the schema's terse 'Include the invoices each payment is linked to' does not convey. It says nothing extra about page, but the schema covers that adequately.

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 (list) and resource (payments) scoped to the Fakturownia/InvoiceOcean account, so the agent can identify it as a read operation on payments. The first two sentences partially restate each other ('Payments recorded in Fakturownia' / 'Returns payments recorded in the account'), but the core purpose is unambiguous.

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 explains what include_invoices does and why it matters (avoid double-booking a transfer), which is usage-adjacent guidance. However, it never names the sibling alternative for recording a payment (fakturownia_record_payment) or states when to prefer this listing over others, so when-to-use is only implied.

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