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

No annotations are provided, so the description carries the full behavioral burden. It does disclose one useful trait – that the session lasts one hour – but says nothing about whether the tool is stateful, what it returns, side effects, or auth requirements.

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 fragments with no filler, and the role-setting 'Optional' is front-loaded. The fragments are slightly disjointed ('No registration...' reads as an aside), but the size is appropriate.

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 no-param, no-output tool the description is nearly adequate, but it omits the relationship to visitor_check_in and what a caller actually receives, which are the details an agent needs to choose correctly among siblings.

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 tool takes zero parameters and the schema is empty with 100% coverage, so there is nothing for the description to document. Baseline of 4 applies for a parameterless tool.

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 names a resource and a scope ('a one-hour visit session'), so an agent grasps roughly what it yields. However, the leading fragment 'Optional greeting' is vague and the description never distinguishes the tool from its obvious sibling visitor_check_in, leaving the action ('hello' vs 'check in') ambiguous.

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?

'Optional greeting' flags that calling it is not mandatory, and 'No registration is required for other tools' implies other tools work without it. But it never states the condition that should make an agent pick visitor_hello over visitor_check_in, 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.