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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds genuinely useful behaviour beyond that: per-product freshness via observedDate, the limit default/max, and the `truncated` flag signalling more rows exist. It does not add much else (no auth, rate limits or ranking-algorithm detail), so a 3 is appropriate against a strong annotation set.

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?

Front-loaded with the core purpose and category list, then scoping rules, then return behaviour, with no filler sentences. Dense but each clause carries distinct, decision-relevant information.

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 carries the return-value burden and does so: best `limit` rows (default 25, max 40), a `truncated` indicator, and how fees are summarised versus the full detail in rate_details. Nothing an agent needs to call this correctly is missing.

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%, so the baseline is 3, but the description adds real semantic value: it defines what the headline home-loan rate means (owner-occupied P&I with LVR band covering 80%), how termMonths ranks published rates, and how customerSegment applies. This goes beyond the one-line schema descriptions.

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 opens with a specific verb+resource ('Current comparison across institutions for a product category') and enumerates the categories, so an agent knows exactly what is returned. It also distinguishes itself from the sibling find_products ('It has no lender filter: for one lender's products use find_products').

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?

Explicit routing rule to find_products when a single lender is wanted, plus per-category applicability for termMonths, customerSegment and loan filters. It states 'Standard products only unless audience says otherwise', giving clear default behaviour and the condition to override it.

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