Create email alias

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

Annotations declare a non-readonly, non-destructive, non-idempotent, closed-world write. The description adds genuine context beyond that: mail is forwarded to the user's inbox, the call returns the new address, and `note` shapes the generated address. It does not address collision behavior when `local` is supplied or whether the alias is enabled on creation, so it is not fully transparent.

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?

Four sentences, front-loaded with the core action and purpose before the parameter guidance. The final sentence is somewhat long but every clause carries usable information; no filler or repetition of schema text.

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?

With zero required parameters, no output schema, and simple flat inputs, the description covers what the tool does, its side effect (forwarding), and its return value. Missing only edge-case behavior around duplicate `local` values or default alias state, which are minor for a create tool of this simplicity.

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, but the description adds meaning the schema does not: it shows the concrete address shape produced by `note` (github.k3f9@domain) versus a random address when omitted. That directly informs how to choose between `note` and `local`, which the schema only describes abstractly.

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 ("Create a new forwarding email alias on the user's own domain") and immediately grounds it in a concrete scenario (signing up to a website without revealing the real address). It is clearly distinguishable from siblings like list_aliases, set_alias_enabled, or send_from_alias, none of which create aliases.

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?

Gives a clear use case (masking the real address for site signups) and a decision rule for the optional `note` param: pass it for a readable address, omit it for a random one. It does not explicitly state when-not-to-use or name a sibling alternative, which keeps it short of a 5.

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