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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety and locality profile is covered. The description adds that it returns destinations, which is useful, but says nothing about pagination, auth requirements, or result limits. With annotations carrying the operational profile, a 3 is appropriate.

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?

Two short, front-loaded sentences with zero wasted words. The key information (what it lists, optional filter) is presented immediately.

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?

Given a simple read-only list operation with one optional parameter and full schema coverage, the description is mostly complete. It could mention return format or pagination, but for this complexity level it is adequate.

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% and the single parameter's purpose ('Only aliases on this domain') is already documented. The description's 'Optionally filter by domain' adds essentially no new meaning beyond what the schema provides.

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 (List) and resource (aliases), and disambiguates the term with a parenthetical '(forwarding addresses)' and mentions destinations. Easily distinguished from siblings like list_mailboxes, list_domains, or list_dns_records.

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?

The word 'Optionally' implies usage for the filter, but the description gives no explicit when-to-use guidance or alternatives. It does not point to get_account_summary or other tools for related info, leaving usage context inferred.

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