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

Annotations already establish read-only, non-destructive, closed-world behavior. The description adds that results are not a cheapest-option ranking or a rate offer, which is useful domain-specific context, but it does not explain the form of the response or any limitations on advice or accuracy beyond that.

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, front-loaded with the use case and a concise prohibition. There is no filler or repetition, and the exclusion is placed immediately after the intended use.

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 a crowded explain/compare sibling set, the description should clarify what the explanation contains and when to choose explain_loan_basics, explain_hesl, or compare_scenarios. It covers scope and a key exclusion but leaves return nature and sibling routing under-specified.

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?

The single optional question parameter has 100% schema description coverage, including sensitive-data refusal behavior and empty-parameter behavior. The description adds no parameter semantics beyond the schema, so the baseline of 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?

The description lists the concrete options it covers (cash, personal or green loan, installer finance, home-loan top-up, and the NSW Home Energy Saver Loan) and frames the use case as comparing them, so the resource is identifiable. It never states explicitly that it returns explanatory or educational content rather than a recommendation, and it does not name the overlapping siblings, so sibling differentiation is only partial.

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?

It gives a clear when-to-use case and an explicit when-not-to-use restriction against ranking a cheapest option or presenting a rate as an offer. It does not route the agent to compare_scenarios, explain_loan_basics, or explain_hesl, which is a gap given the overlapping sibling set.

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