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

Goes well beyond the annotations: it discloses that no e-mail is sent by the call itself but instance triggers may send one, that new users are never created, and that the article is recorded as customer-authored. These side-effect details are exactly what annotations (destructiveHint=true, openWorldHint=true) cannot convey and are critical for a write tool.

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?

Three sentences, front-loaded with the operation class ('WRITE') and the core action, then the side-effect caveat, then the negative constraint. Capitalized emphasis on ONE/EXISTING aids scanning without padding; no sentence is redundant.

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 10-parameter, non-idempotent write tool with no output schema, the description covers prerequisites, trigger behavior, and the endpoint. It omits any mention of what is returned (e.g. the created ticket id), which an agent may need to chain a follow-up call, but that is a minor gap given the otherwise thorough disclosure.

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 meaning the schema cannot: the customer field must reference an existing user and the choice between customer (e-mail) and customer_id (id) is a mutually exclusive input, plus the note/phone article semantics. It does not explain defaults for state, priority, or owner, which the schema handles.

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 ONE new ticket') plus scope qualifiers: for an EXISTING customer, in a group, with a first article attributed to the customer. The 'WRITE:' prefix and 'ONE' immediately separate it from sibling read tools (zammad_get_ticket, zammad_list_tickets) and from update/reply tools.

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 explicit prerequisites and constraints: the customer must already exist ('It never creates new users'), provide either an e-mail or a user id, and the article type is note or phone. It does not explicitly name the alternatives (zammad_reply_to_ticket, zammad_add_internal_note) for adding messages to an existing ticket, so routing guidance is strong but not exhaustive.

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