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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so "Read-only; needs no lease" is largely redundant. What the description adds beyond annotations is genuinely valuable: it explains what each outcome means, including that approval timeouts surface as send_not_approved/send_approval_fell_back and that this is indistinguishable from a stuck draft on the outside.

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?

Purpose is front-loaded in the opening clause and the alternative-interpretation guidance is folded in efficiently. It runs long with nested quotation and a parenthetical outcome-code list, but each clause carries useful information rather than 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?

With no output schema, the description does the heavy lifting by enumerating the outcome categories an agent will see. It leaves the per-record shape (timestamps, message identifiers, error text placement) unstated, which is a minor gap for a diagnostics tool but not blocking.

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 parameter meaning, and it does: inboxId "narrows to one inbox" and limit "defaults to 20" (a default absent from the schema). It omits the limit ceiling of 100, which the schema declares, but the essential semantics are covered.

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 resource (recent send outcomes for this account, newest first) and enumerates the exact outcome categories it surfaces (message_sent, send_failed, send_not_approved, send_approval_fell_back). No sibling tool reports send diagnostics, so an agent can distinguish it from send_draft/send_draft_from_card without opening schemas.

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?

Gives an explicit trigger: "Call this when someone reports that sending did not work, before guessing at causes." It also disambiguates the classic confusion case (a timed-out approval prompt looking like "the email stayed a draft"), which implicitly steers agents away from draft tools. No explicit when-not or named alternatives, so not a 5.

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