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

Beyond readOnlyHint/destructiveHint, the description discloses that data is read live from Plesk, that the main account's password is the SSH password and cannot be reset via chat (must be changed in Plesk), and that zero additional accounts is a normal state. These are exactly the operational caveats annotations cannot express.

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 core action, then layered caveats; every clause carries information an agent needs (password reset limitation, normal-state clarification). The long parenthetical makes it dense but not wasteful.

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?

With no output schema, the description compensates by describing what is returned (main login plus additional accounts with start directory) and by pre-empting the most likely misinterpretation of an empty result. Nothing needed to call or interpret this tool is missing.

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?

There is a single parameter ('domain') and schema description coverage is 100%, so the schema already carries the semantics. The description adds no syntax, format or scope detail about the domain parameter. 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 ('FTP-Zugänge einer Domain auflisten') and immediately splits the result into two distinct classes: the subscription's main account and the additionally created accounts with start directory. This lets an agent distinguish it from create_ftp_account, delete_ftp_account and reset_ftp_password 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?

Explicitly routes the agent: the additional accounts supply the login that reset_ftp_password requires, and it warns that customers rarely know their FTP username. It also defuses a false error signal ('no additional accounts is normal'). It stops short of naming the sibling tools it is not (create/delete), so it is strong context rather than a full when/when-not matrix.

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