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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the bar is lower. The description still adds real value by naming the freshness field (last_checked, which reflects when Homedex verified the listing was live on the agent's site) and by pointing to agent_url as the booking path, though it omits what happens on a missing/delisted record.

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?

Purpose is front-loaded in the opening clause, followed by a field inventory and one short actionable sentence. The field list is long, but each item tells the agent something it can surface to a user, so little of it is wasted.

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?

An output schema exists, yet the description still gives the agent enough of a payload map to answer 'what can I tell the user?' without a trial call, and it covers the booking hand-off. For a one-parameter read tool with full annotation coverage, nothing material is missing beyond error-case behaviour.

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 100% and the single parameter already documents itself with the same example (HX-CT20-00084), so the description is largely restating structured data. Baseline 3 applies; it adds no constraint such as format validation or accepted identifier variants.

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 concrete retrieval action ('Everything about one listing by its Homedex number') and enumerates the payload (price, rooms, tenure, photos, agent, last_checked, nearby sold data), so the agent knows exactly what resource it gets. It never names a sibling, though, and its 'recent sales within 500 m' content overlaps with the nearby_sold tool without clarifying the distinction.

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 only implied: the required Homedex number signals this is for when an ID is already known, and the closing line directs the user to agent_url for bookings. There is no explicit 'use this instead of search_listings when...' guidance and no stated behaviour for an unknown or stale Homedex number.

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