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

Annotations already cover the read-only/open-world safety profile, and the description usefully adds pagination behavior (unfiltered calls return the first page) and an auth requirement (Cotlet API key with access to this app). These are real behavioral facts beyond the annotations, though return shape is not described.

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, each earning its place, with the search capability and no-filter behavior front-loaded. The leading 'Fakturownia (InvoiceOcean):' prefix is mildly redundant with the title but provides app context.

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 5-optional-param list tool with annotations and no output schema, the description covers search mechanics, no-filter pagination, and auth needs. It is essentially complete, though it does not hint at result ordering or page-size limits.

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, but the description adds a constraint not present in the schema: 'Pass one search field' to search, implying the filter fields are alternatives rather than combinable. It also enumerates the searchable fields, reinforcing their meaning.

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 a specific resource (clients) and verb (list/return) plus the searchable fields, so purpose is unambiguous. It implicitly distinguishes from fakturownia_create_client by stating it returns existing clients, but it does not explicitly name any sibling for differentiation.

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 clear when-to-use context ('find a buyer before you invoice them') and the no-filter behavior ('first page of all clients'). It stops short of naming explicit alternatives or exclusion conditions, so it is strong but not fully routing-grade.

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