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

Annotations only supply destructiveHint=true; the description adds the crucial irreversibility fact ('Cannot be unsent'), which is exactly the kind of behavioral trait an agent needs before sending. It also clarifies the visibility semantics of the internal flag, though it says nothing about rate limits or what the call returns.

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, front-loaded with the core action, then the modifier, then the irreversibility warning, then the API mapping. No wasted words and nothing buried.

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 four-parameter write tool with no output schema, the description covers the action, the key modifier, and the irreversibility risk. The only minor gap is that it doesn't indicate the shape of the response (e.g., the created message id), though that is not required here.

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 all four parameters are already documented in the schema, making 3 the baseline. The description restates the internal flag's meaning as an 'internal note hidden from the guest' and adds the logging rationale, but adds no format or syntax detail beyond the schema.

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 (post), resource (message on a reservation's thread), and recipient (the Smoobu user/host), which cleanly distinguishes it from the sibling smoobu_send_message_to_guest. The endpoint reference reinforces exactly what operation is performed.

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 a concrete use condition for the internal flag — 'handy for logging' — which tells the agent when that mode is appropriate. It never states when to prefer this over send_message_to_guest or list_message_threads, so there is clear context but no explicit alternatives or exclusions.

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