Create Email Inbox

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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=false) by disclosing the pricing meter ($0.01 per started 600 seconds), TTL bounds, the fact that a payment result returns an inbox-scoped access_token and capability instead of requiring account setup, idempotency-on-retry behavior, and explicit non-guarantees (SMTP delivery, valid OTP). This is exactly the operational context an agent needs before spending money.

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?

Front-loaded with purpose, then pricing, then auth/idempotency, then included features and caveats – a sensible order with no filler. It is dense and jargon-heavy ('x402', 'capability') at the cost of a little readability.

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 paid, mutating allocation tool with an output schema, the description covers cost, TTL, credential return, retry safety, and feature boundaries. An agent could decide whether to call it and how to retry correctly without consulting anything else.

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 baseline is 3; the description still adds value by tying ttl_seconds to a billing unit ('per started 600 seconds', default $0.01 for 600s) and by explaining the retry semantics of idempotency_key rather than just its pattern. The 60–3600 range is redundant with the schema's min/max.

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 – 'Allocate an inbox' – with the intended scope ('authorized inbound testing'). This immediately distinguishes it from the sibling lifecycle tools list_email_messages, get_email_code, and delete_email_inbox.

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?

Clear context for use ('authorized inbound testing', no account/key setup required) and a note that reads, code polling and deletion are included in the allocation. It never explicitly names alternatives or exclusions, such as when to prefer claim_free_trial or which sibling consumes the returned token, but the operating context is unambiguous.

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