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

Beyond the annotations (which only mark it as a non-idempotent, non-destructive write), the description discloses price and billing behavior ($1.00 per month, $1.00 per call, free on failure) and the daily attachment caps with what happens when the store is full. That is exactly the extra context annotations cannot carry.

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 core purpose and both option flags are front-loaded in the first three sentences, with billing last. It is dense but every sentence carries operational detail; only the attachment paragraph runs a little long.

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 mutation tool with no output schema, the definition covers what is created, its immediate capabilities, the two behavioral flags, cost, renewal source, and failure cost. Nothing an agent needs to decide or invoke correctly 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 coverage is already 100%, so each parameter is documented; the description still adds value by framing open_tickets in terms of ticket_connect_inbox and save_attachments as the email-in file store use case. It stops short of restating every parameter, so it slightly exceeds the high-coverage baseline.

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 names a concrete verb and resource (a new email address on its own subdomain) and gives a literal example, e.g. support@acme.useconecto.com. It is unmistakably distinct from siblings like email_update_inbox, email_list_inboxes, and email_release_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?

It gives clear when-to-use scenarios: open_tickets=true for a support inbox and save_attachments=true for supplier invoices sent to an email-in address, with a pointer to ticket_connect_inbox. It does not explicitly state when not to use this tool (e.g., to modify an existing inbox), which keeps it short of a 5.

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