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

readOnlyHint=true already covers the safety profile, and the description adds that matches are "best matches" (i.e. ranked) and that results carry a listing id plus address, which the absent output schema would otherwise leave unknown. It does not mention truncation/default result count behavior beyond what the schema says, so meaningful but not rich added context.

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 sentences, front-loaded with the purpose, then the follow-up action; every clause carries information. The trailing raw endpoint "POST /v1/rex/Listings/autocomplete" is largely noise for an agent invoking a tool and is the only wasted element.

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 only three simple flat parameters and no output schema, the description supplies what is needed: input semantics (partial address), result content (id + address) and the next call to make. Missing only explicit differentiation from the full search siblings.

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%, so limit, search_string and listing_states are all documented in the schema, and the description adds only the notion that search_string is a partial address. Baseline 3 applies 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?

The description names a specific verb and resource ("quick lookup of listings by (part of) an address") and states the input shape (partial address), so the agent knows this is a prefix/partial matcher rather than a full search. It does not name the nearest sibling, rex_search_listings, so the boundary with it is left implicit.

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?

"Use the id with rex_get_listing" gives explicit downstream routing, which is useful workflow guidance. However, there is no statement of when to prefer this over rex_search_listings (the obvious alternative for listing search), so the agent must infer that this is for autocomplete-style partial input.

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