Create custom alias

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

Annotations already declare this is a non-read-only, non-idempotent, open-world write, so the safety profile is covered. The description adds genuinely useful non-annotation context: the required dependency on alias_options_get, the can_create precondition, and the verbatim pass-through requirement for signed_suffix. It stops short of describing failure behavior when can_create is false or what a duplicate-prefix attempt does.

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 sentences, no filler, and the prefix/suffix framing is front-loaded before the workflow. The second sentence is dense and slightly run-on, but every clause carries a required action.

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 mutation tool with no output schema, the description covers the full call workflow and preconditions well. It omits what the tool returns (e.g. the new alias id) and how errors surface, which would help an agent chain follow-up calls, but nothing needed to invoke it correctly 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, but the description goes further by sourcing parameters to other tools (signed_suffix from alias_options_get, mailbox_ids from mailbox_list) and flagging name/note as optional. The schema alone states signed_suffix's origin, so the added value is modest but real.

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+resource ('Create a custom SimpleLogin alias') and immediately narrows scope with 'with a chosen prefix and suffix', which distinguishes it from the sibling alias_create_random. An agent can tell the two apart without opening either schema.

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 an explicit prerequisite chain: call alias_options_get first, confirm can_create is true, then pass that exact signed_suffix along with mailbox_ids obtained from mailbox_list. This is when-to-use and ordering guidance with named alternatives, not inference.

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