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

Beyond the annotations (readOnlyHint=false, idempotentHint=false), the description discloses two important behaviors: the return is either a message_id or a pending_action_id, and AI-authored factory-visible messages require human approval. That approval gate is exactly the kind of non-obvious behavior annotations cannot convey. It does not cover failure modes or auth requirements, so not a 5.

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 English text is front-loaded and information-dense, but the entire passage is then repeated in Chinese, roughly doubling length without adding content for a single-language reader. The core payload itself is efficient.

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?

There is no output schema, so the description correctly covers return values (message_id vs pending_action_id) and the approval flow. Gaps remain for a 5-parameter mutation with 0% schema coverage: request_id's purpose (likely dedupe/idempotency, especially since idempotentHint=false) and valid visible_to values are undocumented.

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 compensate. It explains the role of order_pack_id, body, line_id and visible_to (though 'visible_to' values are never specified), but leaves the required request_id entirely unexplained and gives no format/semantic detail for line_id. Partial compensation only.

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 verb+resource ('Post order pack message') and immediately names the target object (order_pack_id) and payload (body). It is clearly a write-to-a-specific-order-pack operation, distinguishable from list_order_pack_messages by the verb. It does not explicitly contrast with siblings, keeping it at 4.

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?

The sentence about approval for factory-visible messages implies when the pending_action_id path applies, and implicitly routes to decide_pending_action. But it never states exclusions, prerequisites (e.g., must the order pack be in a certain state?), or explicitly names an alternative tool for reading messages.

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