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

The annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact beyond them, "Needs the owner's sign-in," which tells the agent an authentication prerequisite exists. It says nothing about what is returned or how a bad confirmation number is handled.

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 short, front-loaded sentences with no filler; the resource and key come first and the access prerequisite second. Nothing could be removed without losing information.

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 one-parameter read tool this is close to sufficient, and the auth note is a real addition. However, with no output schema present, the description never indicates what a returned stay contains, leaving the agent guessing at the response shape before calling.

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% for the single parameter, so the schema already defines confirmation as a string confirmation number. The phrase "by its confirmation number" only confirms the parameter is the stay's confirmation identifier, adding little beyond the schema.

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?

"One stay by its confirmation number" gives a specific resource (a single stay record) and the exact lookup key, implicitly contrasting with the plural sibling stays. It stops short of explicitly naming stays or load_stays, so the agent must infer the singular/plural split.

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?

Usage is implied rather than stated: use this when you already hold a confirmation number for a single stay. There is no explicit statement of when to prefer stays or load_stays instead, and no stated failure condition such as an unknown confirmation number.

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