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

The readOnlyHint annotation already establishes the safety profile. The description adds the useful detail that these are values Smoobu *would substitute* (i.e. computed, not stored raw) and cites the underlying endpoint, but says nothing about response shape, size, or whether placeholders can be empty for a reservation lacking certain data.

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?

Front-loads what is returned, then the use case, then the endpoint in one compact block. The enumeration is long-ish but each item conveys concrete return content rather than filler.

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 does the work of telling the agent what comes back by listing placeholder categories, which is the key missing structured information. Complete enough for a simple one-parameter read tool, though it does not describe the key/value shape of the response.

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% and there is a single, self-describing parameter, so the schema carries the meaning. The description adds no syntax or format detail about reservation_id, which is the correct baseline when the schema does the work.

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 (get) and resource (a reservation's message placeholder values), and enumerates the actual content (guest name, dates, nights, price, check-in link, door PINs). This clearly distinguishes it from siblings like smoobu_list_custom_placeholders and smoobu_list_reservation_messages.

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" implies the intended context, but there is no explicit when-to-use vs. when-not, and no sibling is named as an alternative. The agent must infer that this is the read-only lookup tool rather than the send or list tools.

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