Create a disposable test email address

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

With no annotations, the description carries the full burden. It discloses the key behavioral trait that the address is disposable, real, and can receive mail for a short time, which goes beyond the tool name. However, it doesn't mention expiration specifics or side effects, though the parameter schema covers TTL.

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 a single, front-loaded sentence with no filler. It conveys what the tool does, why to use it, and what to do next, all without redundancy.

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 creation tool with one optional parameter and no output schema, the description gives adequate context: purpose, usage, and next step. It doesn't explicitly state the return value format, but the phrase 'Get a fresh, real email address' implies the result, and the overall completeness is strong.

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 input schema provides 100% coverage with a clear description of ttlMinutes, including default, maximum, and meaning. The tool description itself does not add any parameter-specific guidance, so the baseline score 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 clearly states the tool's function: obtaining a fresh, real email address for receiving mail temporarily. It distinguishes itself from siblings by explicitly mentioning the follow-up call to get_test_email_messages, and the title reinforces the purpose.

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 provides a clear usage scenario: sign up for something being tested, then check messages with get_test_email_messages. It names the sibling tool as the next step, but doesn't explicitly state when not to use this tool or compare to alternatives like rent_test_phone_number.

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