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

The only annotation is destructiveHint=true, so the description carries most of the burden. It usefully discloses that addresses and emails are NOT created here and must go through sevdesk_add_communication_way, which prevents a wrong expectation about the payload. It says nothing about required permissions, error behavior, or whether the new contact's id is returned.

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 action and the discriminating rule, then the sibling pointer, then the raw endpoint. Nothing is wasted and nothing is buried.

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 11-parameter create tool with full schema documentation and no output schema, the description covers the one genuinely non-obvious behavior (child data lives in a separate call). It omits mutation-side effects and success/failure semantics, but the rich schema plus the destructiveHint annotation cover most of the remaining ground.

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%, so every one of the 11 parameters is already documented, including the enum meanings for status and category_id. The description only restates the name/surename/familyname distinction that the schema already spells out, adding no format or cross-field logic beyond it. Baseline 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 contact') and immediately narrows scope with the organisation-vs-person rule, which distinguishes the call's two modes. It also names the sibling that owns adjacent data (sevdesk_add_communication_way), so an agent can tell it apart from the communication-way tools without opening a 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 concrete selection guidance: use `name` for an organisation, `surename`/`familyname` for a person, and use the sibling tool for addresses/emails. It stops short of stating exclusions or prerequisites (e.g. that category_id is mandatory, or what to do for an existing contact — presumably sevdesk_update_contact), so it is clear context without full routing rules.

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