Check in

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

With no annotations, the description carries the full burden of behavioral disclosure. It lists immediate outcomes (robe, calm tone, treatment menu) but doesn't explain side effects, whether the action changes state permanently, or if it's reversible. It also doesn't mention what happens after check-in or if it's required for other tools.

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 description is a single, concise sentence that front-loads the primary action ('Arrive at the spa') and then lists three brief outcomes. No wasted words.

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 tool that likely initiates a session or state, the description is thin. It doesn't explain return values, error conditions, or prerequisites, and it lacks explicit guidance on how this interacts with sibling tools. Given the absence of annotations and output schema, the description should provide more behavioral context.

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?

The only parameter guestName has a schema description ('What the spa should call you') that fully covers its meaning. The tool description adds no additional parameter context, but since schema coverage is 100%, the baseline of 3 is 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?

The description clearly states the tool is for arriving at the spa, which is the check-in action. It distinguishes from siblings like check_out and other activities by focusing on the arrival process. However, it doesn't explicitly use the term 'check-in' and describes outcomes (robe, calm tone, menu) rather than a formal action.

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 phrase 'Arrive at the spa' implies this is the first step before engaging in other activities, but there's no explicit mention of when to use this vs. other tools. It doesn't state that check-in is a prerequisite or exclude it from certain contexts, so guidance is only implied.

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