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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read and open-world nature is covered. The description adds that the profile is 'public', implying no auth is required, but says nothing further about rate limits or data freshness. With annotations carrying the safety profile and an output schema carrying the return shape, a 3 is appropriate.

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 tight sentences with no waste: the purpose is front-loaded, and the sibling routing follows immediately. Every clause earns its place.

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?

Purpose, lookup key, and sibling routing are all present, and an output schema exists so return values needn't be explained. Annotations cover the safety profile. The only minor gap is lack of any note about failure behavior for invalid IDs, which is non-critical here.

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 the single 'id' parameter is documented as a host/user ID with an example. The description restates that the id may be a 'host or user id', adding only slight clarity beyond the schema. Baseline 3 is correct when the schema does the heavy lifting.

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 ('Fetch') and resource ('public Airbnb host profile') and specifies the lookup key ('by host or user id'). This clearly distinguishes it from airbnb_room (a stay) and airbnb_search (searching stays), so an agent can identify it without opening the schema.

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?

Explicitly routes the agent to the correct sibling: airbnb_host_listings for that host's properties, airbnb_host_reviews for reviews, and notes airbnb_search finds stays rather than host records. The alternatives and the condition selecting each are named directly.

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