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

The annotations already cover read-only, idempotent, non-destructive, closed-world behavior, and the description adds real substance: the index is city-wide, not suburb-level, so it is a coarse comparison; the response carries the months compared, the source, and the index's stated limits. It also explicitly frames the output as information rather than advice, which sets a useful boundary. It does not discuss error or edge behavior, such as a lease_start after the latest index release, but the output schema covers the return shape.

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 dense sentences are front-loaded with the comparison being made, then the granularity caveat, then what the response carries. Every clause earns its place; the final sentence is slightly packed but nothing is padding.

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 an output schema handling return values and annotations covering safety, the description supplies the remaining essentials: data source, comparison window, granularity limits, and the non-advice framing. It leaves out only edge behavior, such as what happens when lease_start postdates the index series.

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 the schema already documents all four parameters and the baseline is 3. The description adds meaning beyond that by constraining city to the eight capitals as a city-wide series rather than a suburb-level one, and the phrasing 'any proposed new rent' signals that proposed_rent is optional.

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 precise verb and resources: it compares a weekly rent and a proposed new rent with ABS rents index movement since lease start. The qualification that the index is city-wide, not suburb-level, separates it from the granular area_rents and vic_rents siblings.

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?

The context implies using the tool when someone wants to sanity-check a rent change against the index, and it implies a city-wide rather than a suburb-level question. However, the description never states when not to use the tool, nor does it name area_rents, vic_rents, or any other alternative for those cases, so an agent must infer the routing.

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