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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description adds real behavioral context beyond that — a time-dependent rate change (contracts from 7 October 2026), a hard scheme end date of 2029, and multiple caps that determine the outcome. It does not state the return shape or how the candidate amounts are surfaced, but for a pure read-only calculator the disclosure is strong.

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?

The definition is front-loaded with the scheme identity and then packs the eligibility and calculation constraints into dense, purposeful clauses with no filler. It is a single long run-on stretch of semicolon-separated conditions rather than clearly structured sentences, which costs it a point but not more.

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?

For a four-parameter calculator with a fully described schema and no output schema, the description supplies everything needed to invoke it correctly: eligibility gates, the formula, the caps, and the date-dependent rate. The only gap is that it does not say what the tool actually returns (e.g., the qualifying refund amount and which cap binds), leaving the result shape to inference.

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 does add interpretive value by explaining how price, taxPaid and mortgage interact in the lesser-of rule and the 70% mortgage threshold, but it does not clarify contractDate's self-build drawdown behavior beyond what the schema says.

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 the specific scheme (Ireland Help to Buy refund) and enumerates the exact computation rule — lesser of €35,000/€30,000, 10% of price, or 4-year tax+DIRT — so the resource is unambiguous. It never uses an explicit verb like 'calculate' or 'estimate', which keeps it just short of a 5, though the scheme name and eligibility conditions clearly separate it from the other jurisdiction-specific calculators in the sibling list.

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 is implied by the stated eligibility conditions (first-time buyer, new build or self-build, price ≤ €500,000, mortgage ≥ 70%, scheme runs to end of 2029), which tell an agent when the tool applies. However, there is no explicit when-not guidance and no pointer to alternatives such as ireland_what_can_i_claim or ireland_budget_2027_take_home for users who turn out to be ineligible.

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