Enable or disable the catch-all of a mailbox

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

With annotations already indicating a non-read-only, potentially destructive mutation, the description adds useful behavioral context: it returns the updated subscription, and it warns about increased unsolicited mail when enabled and refusal when disabled. It does not contradict the annotations.

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, each earning its place: the action and return value, the behavioral consequence, and the sibling alternative. The core statement is front-loaded, with no filler or repetition.

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 simple two-parameter tool with a rich input schema, an output schema, and strong annotations, the description covers the action, the return value, the practical impact, and the alternative tool. Nothing essential 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?

Schema coverage is 100%, so the baseline is 3. The description adds semantic value by mapping enabled:true to 'on' and enabled:false to 'off' and explaining the resulting mail routing behavior, going beyond the schema's brief descriptions.

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: 'Turns the catch-all on (enabled: true) or off (enabled: false) for an email subscription.' It clearly differentiates from the sibling eurodns_email_set_alias by noting the scope is domain-wide rather than a single named address.

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?

Provides explicit alternative guidance: 'For one named address use eurodns_email_set_alias.' It also explains the practical consequences of each setting (delivering unknown addresses vs. refusing such mail), which helps an agent decide when to call this tool.

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