Send a DM to a buyer (requires confirm + your token)

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

Adds genuinely useful behavior beyond the annotations: the call consumes the user's own token with dm.write scope, and omitting confirm:true yields a preview rather than a real send — the single most important safety fact here. It still says nothing about rate limits, failure modes, or whether a sent DM can be undone.

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 tight sentences with zero filler, front-loaded on what the tool does, then prerequisites, then the confirm behavior. Nothing repeats the title or restates the obvious.

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 three-parameter mutation with no output schema, it covers purpose, prerequisites, auth scope, and the dry-run default, plus a hint at the return value ('a preview only'). Only error/idempotency behavior is left uncovered.

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 carries the burden. It explains participantId ('buyer's numeric X user id') and, valuably, the confirm semantics (preview vs. actual send), but leaves text — including its 10,000-character bound — entirely to the schema. Two of three parameters get meaning, one does not.

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?

Specific verb+resource ('Send an approved reply as an X direct message') with a stated prerequisite (approved reply, user's own token). It implicitly distinguishes itself from draft_buyer_reply by insisting the reply is already approved, but never names that sibling explicitly, so differentiation requires inference.

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 clear context for use: the reply must already be approved, the participant must be identified by numeric X user id, and confirm:true is the switch between preview and real send. It does not state exclusions (e.g., when to prefer drafting first), so it stops short of full when/when-not guidance.

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