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

Annotations already declare destructiveHint=true, openWorldHint=true, idempotentHint=false, so the risk profile is known; the description still adds real value by disclosing that the message is stored in SENT, that reply_to fields thread and quote the original, and that delivery goes to real external recipients. It stops short of stating irreversibility, permission/verification requirements, or rate limits.

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 dense sentences with the [publish] tag front-loading the action class, then mailbox selection, then threading behavior, then the delivery warning. No filler, though the parenthetical parameter list is a slightly awkward mid-sentence insertion.

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 10-parameter, non-idempotent, destructive outbound-send tool with no output schema and zero schema descriptions, the definition covers the sending mailbox and reply threading but leaves key gaps: which account to use if none is given, whether subject/to alone suffices for body content, what a successful send returns, and whether the mailbox must be verified first.

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 must carry the load, and it does explain 4 of 10 parameters: email_account_id/email_account_uuid select the sending mailbox and reply_to_email_message_id/uuid control threading and quoting. The remaining six (to, cc, bcc, subject, text, signature) get no treatment, and "signature" in particular is ambiguous (account-level vs. inline appended text).

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 ("Send an e-mail from one of the merchant's mailboxes") plus two concrete side effects (stored in SENT, threaded as reply with quoting). The closing line "Delivered to real recipients" implicitly separates it from save_email_draft, but no sibling is named explicitly, so it falls short of full sibling differentiation.

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 a publishing/sending context via the [publish] tag and "Delivered to real recipients," which nudges an agent away from draft tools, but it never names save_email_draft or draft_supplier_email as alternatives. There are no stated prerequisites (e.g., an existing email account is required to select a mailbox) and no when-not-to-use guidance.

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