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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely non-obvious behavior: criteria combine with AND unless the `in` type is used, results are paged with offset/limit, and next_offset indicates continuation. It omits anything about result caps or what the record payload looks like, keeping it below a 5.

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?

Front-loaded with the verb and resource, then pagination, then the field crib sheet, then the alternative tool. A single dense paragraph with no filler, though the inline field enumeration is longer than strictly necessary.

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?

Five parameters with nested criteria/order_by objects and no output schema, so the description carries real burden — and it does cover filter semantics, paging continuation, and where field names come from (rex_describe_search_fields). The absence of any description of returned listing shape or result-size limits leaves a small gap.

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%, so baseline is 3; the description earns above that by explaining the AND-conjunction model, the OR exception via `in`, and by naming concrete useful field paths (system_listing_state, adr_postcode, attr_bedrooms) with an example value. It does not restate limit/offset bounds, which the schema already handles.

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 and resource ("Search listings (properties for sale or rent)") and immediately names the sibling that serves a narrower purpose, rex_autocomplete_listings. An agent can distinguish this from rex_search_properties and the autocomplete tools without opening a 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 address lookups to rex_autocomplete_listings and defines the AND combination semantics for filters. It stops short of saying when to prefer this over rex_search_properties or how to choose search_state, so it is clear context rather than full when/when-not guidance.

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