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

Annotations already declare readOnlyHint=false, openWorldHint=true, destructiveHint=false; the description usefully adds that nothing is sent externally, the record is reversible, and it discloses the auth requirement (Cotlet API key with access). This meaningfully enriches the safety profile beyond the annotations, though it doesn't cover pagination/response 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?

Front-loads the action and required-field info, then behavioral notes. Minor redundancy from restating the brand prefix and rephrasing 'Add a client' as 'Creates a client record,' but overall 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 create tool with no output schema and annotations carrying the safety profile, the description covers required fields, edge cases, side effects, and auth. The only gap is what the call returns (e.g., new client ID), which an agent would need to chain into subsequent calls.

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 real semantic value: it clarifies that only name is required and documents the conditional relationship between company=false and last_name. This goes beyond the per-field schema descriptions.

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 ('Add a client to your Fakturownia client list. Creates a client record.'), which cleanly distinguishes it from siblings like fakturownia_list_clients or fakturownia_create_invoice. Sibling differentiation is implicit via the brand/app name rather than explicitly routing away from alternatives.

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 when-to-use context: it can be run without confirming first because nothing is sent and the record is editable/deletable. It also flags the required-field minimum and the private-person case. It stops short of naming a specific alternative tool or exclusion condition.

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