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

Beyond annotations, the description discloses that guests receive no message, invalid guest IDs are refused, hosts only may use it, and it returns changed and total checked-in counts. These are important behavioral details for a mutating host-only operation.

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 short and front-loaded, but the first two sentences slightly repeat the check-in/undo action. The remaining sentences carry useful constraints and return information without excessive length.

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 usefully explains the return counts. It also covers host-only authorization, missing-guest refusal, notification behavior, and undo semantics, leaving little an agent needs to infer before calling it.

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%, so the baseline is 3. The description adds meaningful semantics by explaining that undo reverses the check-in and that guest IDs not on the guest list are refused.

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 states a specific verb and resource: marking guests as checked in or undoing it. It is clear what the tool does, but it does not explicitly differentiate itself from sibling tools such as approve_guests.

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?

It clearly establishes the check-in-at-the-door context and the undo variant, and notes that hosts only may use it. It does not explicitly name when to use a sibling tool instead, but the intended use case is unambiguous.

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