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

Beyond the annotations (non-read-only, non-destructive), the description adds valuable behavioral context: inboxes are temporary, no setup is needed, and the tool returns both an address and an inbox_token. This is especially useful because there is no output schema to document the return shape.

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?

Every sentence earns its place: purpose, return values, when to use it, and lifecycle guidance. It is front-loaded and compact, 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?

For a tool with one optional parameter and no output schema, the description is complete: it explains what is created, what the caller receives, when to use it, and that inboxes are temporary. Nothing critical is missing for an agent to invoke it correctly.

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 only parameter, review, is fully described in the input schema as an optional label for bookkeeping. Since schema description coverage is 100%, the description doesn't need to compensate; it also doesn't add further meaning, 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 states a specific verb and resource: create a disposable email inbox for monitoring. It clearly distinguishes itself from siblings like check_inbox (read) and create_review (review handling) by describing its exact role in the testing workflow.

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 explicitly says to use this instead of asking the human for an email account or a third-party inbox API key, and even advises creating a fresh inbox per test persona. It doesn't explicitly name the sibling check_inbox as the counterpart for reading, but the context makes the division of labor clear.

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