Update mail forwarder

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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false; the description adds genuinely useful detail beyond that by warning that fwd_addresses replaces the entire list rather than appending, and that an interactive confirmation may occur. It stops short of saying whether omitted fields are preserved and how to clear a comment.

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 short sentences, front-loaded with the replacement semantics and the destructive list-overwrite warning before the confirmation caveat. No filler.

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?

An output schema exists so return values need no explanation, and the destructive overwrite is flagged. However, for a destructive mutation with an optional-field design, the description omits how partial updates behave and how to clear or leave a field unchanged, which an agent needs before calling it.

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 75% and the schema already describes fwd_addresses as the 'New full list of destination addresses', so the description's replacement note is largely redundant with it. The description adds nothing about the comment parameter (whether an empty value clears it) or about address/vserver identifying the target forwarder.

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: replacing the destination list and/or comment of an existing e-mail forwarder. The 'update/replace existing' framing separates it from create_mail_forwarder and delete_mail_forwarder in the sibling list, though no sibling is named explicitly.

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?

Implies usage (modify an existing forwarder rather than create one) and notes that a confirmation prompt may appear, but gives no explicit when-to-use vs. create_mail_forwarder guidance, no preconditions (must the forwarder already exist?), and no statement about what happens if a field is omitted.

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