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

Annotations cover the safety profile (readOnly=false, idempotent=false, openWorld=true, destructive=false), so the bar is lower. The description still adds real behavioral value by disclosing the two fulfilment paths — immediate booking when signed in vs. booking after e-mail confirmation — which the annotations do not convey.

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, front-loaded with the action and then the prerequisites and flow. The parenthetical multilingual synonyms add bulk but serve a real purpose for a multilingual real-estate agent.

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 7-parameter, 4-required mutation tool with no output schema, the description covers the core inputs and the confirmation flow but omits the phone parameter, the purpose of listing_id, party_size limits, and what the caller receives on success or failure. Adequate but with clear gaps.

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 description coverage is only 14% (only 'language' is documented), so the description must compensate. It does map 'name, e-mail and number of people' to name/email/party_size and explains where viewing_id comes from, but leaves listing_id and phone unexplained, so the gap is only partially closed.

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+resource ('book a place at an open viewing') and even provides the multilingual synonyms a user might speak. It names get_listing as the source of viewing ids, but does not differentiate itself from neighbours like apply_for_listing or register_purchase_interest, which are also booking/reservation actions.

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 gives clear context: this is for open viewings and the viewing id must come from get_listing first, and it explains the signed-in vs. e-mail-confirmation paths. It stops short of stating when not to use it versus the other enquiry/reservation siblings.

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