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

Annotations already declare the write, non-idempotent, side-effecting profile, so the bar is lower. The description still adds real context beyond them: Billomat assigns the client number (so the agent should not supply one) and nothing is dispatched to the customer. It omits what the call returns and any failure modes, which keeps it from a 5.

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, none wasted, with the operation type front-loaded. Each sentence carries a distinct fact: operation, number assignment, no external notification, duplicate check.

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 an 18-parameter write tool with no output schema and no required fields, the description covers the operation, the side-effect boundary, and the duplicate risk. It does not tell the agent what the response contains or which fields are practically required for a usable client record, leaving a small 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 description coverage is 100% across all 18 parameters, so the schema fully carries parameter meaning. The description adds no field-level detail (e.g. which fields matter for an individual vs. company client) beyond what the schema already states, so the baseline of 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 ('create a new client (customer) in Billomat') and leads with 'WRITE:', which immediately separates it from the many billomat_get_* and billomat_list_* siblings. An agent can distinguish it from billomat_update_client and billomat_create_article without opening any schema.

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 an explicit precondition naming a sibling tool: 'Check billomat_list_clients first to avoid duplicates.' That is actionable routing guidance. It stops short of 5 because it never states when not to use this tool or how it relates to billomat_update_client for existing records.

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