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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered by structured data. The description adds the useful detail that results pair aliases with their destinations, but says nothing about pagination, result limits, or ordering. With annotations carrying the safety burden, this is adequate but thin.

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 sentences with no filler; the core purpose leads and the filtering behavior follows. Every clause earns its place.

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 read-only list tool with full annotation coverage and a fully documented single parameter, the description covers purpose, what it returns, and filtering. It is nearly complete, missing only minor details such as whether results are paginated or whether the domain must match exactly.

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 optional 'domain' parameter is already documented. The description's 'Optionally filter by domain' restates the schema without adding syntax, matching behavior, or format details, so the 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 (List) and resource (email aliases), and goes further by defining what an alias is (forwarding addresses) and what the tool returns (their destinations). It is trivially distinguishable from siblings like create_alias, delete_alias, list_mailboxes, and list_domains.

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 description says the domain filter is optional, which is light usage guidance for the single parameter, but it never states when to reach for this tool versus list_domains or list_mailboxes. Usage is implied by the resource name rather than explained.

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