Create a 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, and it delivers meaningful traits: the address is unique, immediately receivable, needs "nothing to set up," and notably "Makes no API call." That last point usefully tells the agent there is no network round-trip, rate limit, or auth wall. It omits any note on persistence, expiry, or cleanup expectations.

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?

Three short sentences, front-loaded with the core purpose and escalating to a usage rule and a behavioral caveat. No sentence is filler; even the terse "Makes no API call" 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 zero-required-parameter generator with no output schema, the description covers purpose, the intended per-test usage pattern, and the key behavioral fact that no API call occurs. It could go further on what the returned address looks like or whether addresses expire, but nothing critical to correct invocation 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 description coverage is 100%, so the schema already explains domain (with default and privacy advice) and prefix. The description adds nothing about either parameter, which is acceptable when the schema does the work. Baseline 3 applies.

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 ("Return a new, unique address that can receive email immediately") and implicitly separates itself from the consumer siblings (wait_for_email, read_email, delete_emails). It never names a sibling or explicitly contrasts its role, so it stops short of a 5.

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 concrete usage direction: "Use one address per test so tests never read each other's mail," which tells the agent the intended lifecycle pattern. There is no when-not guidance or explicit routing to alternatives, but the context for calling it is clear.

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