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

No annotations exist, so the description must carry the full behavioral disclosure burden. It only mentions 'receive-only' and 'temporary or permanent', which are more about purpose than side effects. It does not disclose expiration behavior for temporary inboxes, whether ttlSeconds is enforced, permissions needed, or what happens if the localPart already exists.

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?

One short sentence with no filler or redundancy. It front-loads the action and resource, and every word adds meaning.

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?

With 4 parameters, 0% schema coverage, no output schema, and no annotations, the description is too thin for safe invocation. It omits what localPart means, how TTL applies to temporary inboxes, and what the created inbox response looks like. The sibling set clarifies the action type but not the full call contract.

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 0%, so the description needs to compensate. It maps to 'kind' via temporary/permanent and hints at 'domain' with 'configured inbound domain', but the required 'localPart' and the optional 'ttlSeconds' are completely unexplained, leaving an agent without enough meaning to construct valid arguments confidently.

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 (create), a concrete resource (receive-only email inbox), and key qualifiers (temporary or permanent, on the configured inbound domain). This is clearly distinct from sibling tools like inbox_get, inbox_list, and inbox_delete, which perform different operations on inboxes.

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 implies the tool is for creating a new inbox, but it gives no explicit guidance about when to use this versus alternatives, such as inbox_webhook_create. No exclusions or conditions are stated, though the unique 'create inbox' purpose makes the intended context inferable.

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