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

Beyond the annotations (which only say it is a non-read-only, non-destructive, open-world write), the description discloses the real behavioral traits: mailbox existence is NOT pre-checked, a missing mailbox causes the action to be rejected with nothing changed, and the value is passed unchanged into a single Plesk address field. It also warns that multi-recipient strings and display-name formats are rejected downstream by Plesk, not here.

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?

The core action is front-loaded, followed by the requirement, then the failure-mode caveat and the pre-check advice. Every sentence carries information, though the German phrasing stacks several clauses into the final sentence.

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 4-parameter mutation tool with no output schema, the description covers the essential decision inputs: prerequisite, conditional requirement, and failure semantics. Return-value or permission details are omitted, but annotations and the absence of an output schema make those less critical.

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 the schema already carries the parameter documentation. The description reinforces the target_address-required-when-enabled rule but adds little semantic detail the schema does not already contain, so the baseline of 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 pair and resource: activating or deactivating forwarding of an existing e-mail account to an external address, with a concrete example. It is unambiguous about scope, but it never distinguishes itself from the adjacent sibling set_email_alias, which is the most likely confusion for an agent picking between the two.

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 clear conditional guidance: target_address is mandatory when enabling, and it explicitly tells the agent to call get_email_accounts first rather than guessing a mailbox name. There is no explicit statement of when *not* to use it (e.g. versus set_email_alias), so it stops short of full routing guidance.

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