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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description earns credit for disclosing the pricing basis (Cape Town, standard quality, excl. VAT), which materially affects interpretation of the returned rates. It omits result-size/pagination behavior, which is the main remaining gap for a listing endpoint.

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, zero filler, with the core payload description front-loaded before the filtering hint. Every clause carries information an agent would otherwise have to guess.

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, the description correctly takes on the burden of describing returned fields (codes, units, base rates) and the assumptions behind the rates. For a 2-optional-param read tool this is nearly complete; only result volume and whether rates are per-unit are left 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?

Schema coverage is 100% — both parameters already carry descriptions with examples ('geyser', 'tile'; roofing, walls, painting, etc.). The description's 'Filter by category or keyword' merely restates that and adds no matching semantics (substring vs exact, multi-word behavior, AND/OR combination of the two filters). Baseline 3 applies.

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 ('Lists the building and renovation items that can be priced') and enumerates what each record carries: codes, units and base rates. That is well beyond a tautology. It stops short of naming how it differs from the sibling estimators (estimate_new_build, estimate_works, roof_replacement_estimate), so the catalog-vs-calculation distinction is only implied.

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?

'Filter by category or keyword' tells the agent how to narrow results but never says when to reach for this tool instead of the estimator siblings, nor whether it is a prerequisite lookup step for them. Usage is inferable (look up rates before estimating) but not stated.

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