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

Adds real behavioral context beyond the annotations: the message is irreversible ('Cannot be unsent'), which corroborates the destructiveHint=true, and internal=true changes guest visibility. It does not cover auth requirements, rate limits, or notification side effects, so it is helpful but not exhaustive.

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 tight sentences, front-loaded with the action and recipient, with the caveat and flag semantics following. The trailing raw endpoint reference is mildly redundant but does not bury the key information.

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 simple irreversible write with 100% schema coverage and no output schema, the description supplies recipient, visibility semantics, and irreversibility. Nothing critical is missing, though return/confirmation behavior is left unstated.

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. The description only restates the internal flag's meaning with a use-case gloss and says nothing new about subject, message_body format, or reservation_id beyond the schema, so the baseline 3 applies.

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 a message) and resource (a reservation's message thread) plus the recipient (the host), which cleanly separates it from the sibling smoobu_send_message_to_guest. An agent can pick the right tool without opening either schema.

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?

Explains a concrete usage scenario — internal=true for a note hidden from the guest, described as 'handy for logging' — which tells the agent when the flag matters. It never names an alternative tool or an explicit when-not, so it stops just short of full routing guidance.

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