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

Annotations already declare readOnlyHint=false and destructiveHint=true, and the description adds the auth requirement ("send scope"), which is genuine context beyond the structured fields. However, it never explains why the operation is flagged destructive — i.e. that sending dispatches a real message over email/Instagram/Twitter and cannot be recalled — nor does it mention rate limits or failure handling.

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?

Two short, front-loaded sentences with no filler; the core action comes first and the scope requirement second. Brevity tips slightly into under-specification rather than waste.

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 five-parameter mutation tool with a destructive flag and no output schema, the description leaves key questions open: what a successful send returns, whether the message is immediately delivered or queued, and what happens on channel failure. The auth prerequisite alone does not cover this complexity.

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 100%, so the channel enum, subject-email-only note, and recipient_id format are all already documented. The description adds nothing about parameter semantics beyond naming "channel" and "conversation"; baseline 3 applies since the schema carries the load.

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 ("send a message") and adds scoping ("through a specific channel in a conversation"), so an agent knows this dispatches an outbound message rather than creating a draft or approving one. It does not, however, distinguish itself from siblings like create_conversation_message or approve_message, which sit closely to this capability.

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?

"requires send scope" is a useful precondition, but there is no guidance on when this tool should be chosen over create_conversation_message, approve_message, or retry_message. The agent is left to infer the workflow position of an actual send versus draft/approval steps.

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