message.send

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

With no annotations provided, the description carries the full disclosure burden, and it does so thoroughly: no network connection is opened, nothing leaves the body, the policy gate is passed, a signed decision record is left, and refusal/deferral outcomes are specified. This gives a complete behavioral picture.

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 description is dense but every sentence earns its place: core behavior, usage guidance, policy outcome, approval behavior, and return value. The most important disambiguation—queueing rather than delivering—is front-loaded.

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?

Despite having no output schema and no annotations, the description fully specifies the return shape, error/refusal statuses, approval flow, and policy context. An agent has enough information to invoke this tool correctly and interpret its result.

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, but the description adds useful meaning: the host is lower-cased and checked against the egress allow-list, and the _ref interaction with operator approval and ref-reuse refusal is clarified. This goes beyond the schema without being redundant.

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 uses a specific verb and resource: it 'queues one message in this tenant's outbox on this machine' and explicitly says it is not delivering the message. This clearly distinguishes it from message.read and from any actual network-send behavior the name 'send' might imply.

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 explicitly states when to use the tool ('Use it to hand off a message, not to deliver one') and points to the operator-run delivery step as the separate follow-up. It also explains policy approval/deferral behavior so the agent knows when the call will be queued versus held for an operator.

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