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 clear and the description carries less burden. The description usefully pins the assessment period (1 April 2026 – 31 March 2027) and the tax year (2026–27), which the annotations do not. It says nothing about the shape of the result (rebate percentage? surcharge amount? net saving?), which is the main remaining gap.

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?

A single dense sentence with no filler; the country, the periods, and the varying dimensions are front-loaded. It is information-rich rather than padded, though the stacked clauses make it slightly heavier than needed.

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 six-parameter calculator with no output schema, the description covers scope and period but not what fields come back or how the two interacting calculations (rebate vs surcharge) relate. Adequate to select the tool, but an agent still has to open the schema and infer the return value.

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 all six parameters (age, family, income, premium, children, hasCover) are already documented in the schema. The description confirms the key axes (income tier, single or family, age band) but adds no unit, format, or threshold detail beyond what the schema supplies. 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 resource (private health insurance rebate plus Medicare Levy Surcharge) and names the dimensions it varies on: income tier, single/family, and age band. It also frames the answer as 'whether hospital cover saves you tax', so an agent knows what the tool computes. It doesn't differentiate itself from named siblings, but the jurisdiction-prefixed naming makes the family separations obvious.

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 closing phrase 'whether hospital cover saves you tax' implies the use case (comparing having cover vs paying MLS), but there is no explicit when-to-use guidance, no prerequisites, and no mention of which sibling tool to pick for a different country's benefit question.

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