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

The annotations already declare destructiveHint=true, so the safety profile is carried structurally; the description adds the underlying API call ('sevdesk: POST /CommunicationWay') but nothing about what happens to an existing main communication way when main=true, duplicate handling, or error behavior. With annotations present, adding the endpoint is useful but the behavioral picture remains thin.

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-loaded with the purpose in the first sentence and the key_id guidance immediately after; no filler. The trailing 'sevdesk: POST /CommunicationWay.' is the weakest line since it restates an implementation detail the agent cannot act on, but the overall length is 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 five-parameter creation tool with no output schema, the description covers the input side adequately but omits what the call returns (e.g. the new communication way id) and any permission or failure considerations. It is minimally sufficient rather than complete.

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 parameter including key_id's enum-like values and default is already documented structurally. The description's only addition is recommending 2 as a default, which is marginal reinforcement of what the schema states, so the baseline 3 is appropriate.

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 states a specific verb ('Attach') and resource ('email address, phone/mobile number or website to a contact'), which is more precise than the title's 'Add'. It also names the sibling tool sevdesk_list_communication_way_keys, so an agent can distinguish this write tool from the related read/list tools in the same family.

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 one concrete usage hint for the key_id parameter ('2 Arbeit/work is a good default') and routes the agent to sevdesk_list_communication_way_keys for valid keys. However, it never says when to use this tool versus sevdesk_update_contact or when attaching a communication way is appropriate, so the guidance is implied rather than explicit.

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