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

The readOnlyHint annotation already establishes the safety profile. The description adds real value by disclosing the sensitive contents returned (door PIN codes, online check-in link, balance) that an agent would not otherwise know about from the schema.

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 front-loaded sentences followed by the endpoint reference; the enumeration is informative rather than wasteful. Slightly list-heavy but every element earns its place by revealing return contents.

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?

With no output schema, the description compensates by enumerating the returned placeholder contents, and the annotations cover the safety profile. Complete enough for a single-parameter read tool, though it could note the return structure more explicitly.

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% for the single reservation_id parameter, so the schema carries the semantics. The description only echoes 'for this reservation' and adds no format/syntax detail beyond the schema, making the baseline 3 appropriate.

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 and resource ('Get every placeholder value... for this reservation') and enumerates the contents (guest name, dates, price/balance, check-in link, door PIN codes). It is distinguishable from siblings like smoobu_list_custom_placeholders or smoobu_get_reservation.

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?

'Useful for drafting a guest message' gives a clear use-case context, but there is no explicit when-to-use-vs-alternative guidance and no exclusion conditions relative to the siblings that also return reservation/message data.

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