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

Beyond the annotations, the description discloses two useful behavioral facts: a write scope is required and the pending_approval status diverts the message into a review queue rather than sending. This is real context that the readOnlyHint=false and destructiveHint=true annotations do not convey. It does not explain the destructive/irreversible aspect implied by destructiveHint=true.

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 short sentences, no filler, with the core operation front-loaded followed by the status special-case and the auth requirement. Every sentence carries information that affects how an agent should call the tool.

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 mutation tool with five required parameters, no output schema, and annotations that only flag it as non-read-only/destructive, the description supplies the key missing context: write scope and the review-queue routing. It remains silent on return values and failure behavior, which is a minor gap given there is no output schema.

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 would be 3, but the description adds genuine meaning beyond the schema: it explains what the pending_approval enum value does operationally ('places it in the human review queue instead of sending'), which the schema's 'initial message status' label 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?

The description names a specific verb and resource: 'create a message in a conversation'. An agent can immediately grasp the operation. It does not explicitly distinguish itself from siblings such as send_channel_message or approve_message, which is the main clarity gap.

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 provides one concrete usage cue: setting status to pending_approval routes the message to the human review queue instead of sending it. However, it gives no guidance on when to use this tool instead of the sibling send/approve/reject tools, so alternatives are left to inference.

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