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

With no annotations, the description carries the full burden and does reasonably well: it discloses the free tier, an explicit rate limit (20 calls/day per client), the upstream data source, the fact that legal rules are summarized as 'information, not legal advice', and the aggregate granularity of the result. It omits any authentication or failure/empty-result behavior, which keeps it short of 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?

It is a compact block of roughly 60 words that front-loads the user-facing question and then immediately gives scope, source, limits, and disclaimer. No sentence is filler, and the practical constraints (free, rate-limited) appear before the caveat.

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 no output schema and one simple parameter, the description does the work of describing what comes back (average asking rent plus a rent-control rules summary), the data vintage, and the cost/limits. It is close to complete; only result-shaping details such as units or update lag are unstated.

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?

There is a single parameter with 100% schema description coverage, so the schema already carries the syntax and the 'Dublin 4' / 'Ardee' examples. Baseline 3 is appropriate; the description adds only the scope note that results are county-level aggregates regardless of how specific the area input is.

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+resource: it returns the latest average asking rent for an Irish county plus a summary of Irish rent-control rules, and it names the data source (CSO/RTB RIQ02). It hints at paid siblings via the 'Free:' framing but never names them, so sibling differentiation is implicit rather than explicit.

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 context is implied rather than stated: 'Free:' and the '(all bedrooms, all property types)' scope suggest this is the low-cost county-aggregate option and that bedroom-specific queries belong elsewhere. No sibling tool is named and no explicit when-not condition is given, so the 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.