Create alias

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

Annotations already establish that this is not read-only and not destructive. The description adds useful behavioral context: the alias address is formed from the local part plus the mailbox domain, and messages sent to the alias are delivered to the mailbox. It does not discuss conflict or duplicate behavior, but the annotations lower the burden here.

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?

The description is two short sentences with no filler. The core action is front-loaded, and the second sentence provides the essential mechanics of alias construction and delivery. Every sentence 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 two-parameter create operation, the description is complete: it identifies the target mailbox, explains how the alias address is formed, and states the delivery outcome. With annotations covering the safety profile and the schema covering the parameters, nothing essential is missing for correct invocation.

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?

The schema already documents both parameters with 100% coverage, including mailboxId's meaning and local_part's validation rules. The description echoes the relationship between local_part and the mailbox domain but adds no new parameter-level semantics beyond the schema, so the baseline of 3 is appropriate.

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?

The description opens with a specific verb and resource: 'Create an alias for the given mailbox.' It then explains how the alias address is constructed and where messages are delivered, making the tool's purpose unambiguous and distinct from sibling list/delete alias tools.

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 clearly implies when to use this tool, but it gives no explicit guidance about alternatives or exclusions. It does not mention, for example, that listing or deleting aliases should be done with sibling tools, so usage context is left mostly to inference.

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