Create a disposable mailbox

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

With no annotations provided, the description carries the burden of disclosing behavior. It discloses that the tool creates a mailbox, returns an address and id, and randomizes both name and domain when invoked without arguments. It does not mention lifecycle details like expiry, but the core side effect and return contract are 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?

Two sentences convey purpose, return value, default behavior, and integration with sibling tools. The most important information is front-loaded, and every sentence earns its place with no redundant filler.

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?

The tool is simple with one optional parameter and no output schema, so the description's explanation of returned values ('address to paste into a signup form' and 'id used by the other tools') is enough for an agent to invoke it correctly and use its result. Nothing essential 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 schema already documents localPart well. The description adds value by stating that the domain is also random when no arguments are given, and by signaling that omitted arguments are the recommended default, not just a fallback.

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 states a specific verb, resource, and outcome: 'Create a temporary email address.' It also clarifies the returned artifacts (address and id) and distinguishes the tool from its siblings, which all consume or manage mailboxes rather than create them.

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 gives clear guidance on the common default usage: 'Without arguments you get a random name on a random domain, which is what you usually want.' It does not explicitly name sibling alternatives or state exclusions, but the create-vs-consume distinction makes the intended use clear.

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