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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The one genuine addition is that results are ranked by total cost, a real behavioral trait; the listed return keys largely restate what the existing output schema already provides.

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 short sentences, front-loaded with the core action and ranking behavior. The trailing list_bundles pointer is minor padding but not harmful.

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 an output schema present, the description need not enumerate return values, and annotations cover safety; the schema fully documents inputs. It is complete for correct invocation, missing only guidance on how this comparison tool relates to the other mortgage calculators.

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% for both parameters, including nested offer fields (rate, bank_name, duration_years, insurance_rate), so the schema carries parameter meaning. The description adds nothing about parameter format or constraints, which is acceptable at this coverage level.

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 (compare multiple mortgage offers) plus a scope detail (sorted by total cost), which is enough to separate it from single-offer calculators like calculate_mortgage or calculate_loan_payment. It never names a sibling explicitly, so differentiation is implied rather than stated.

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?

There is no when-to-use guidance and no comparison against the many mortgage/loan siblings (calculate_mortgage, calculate_us_mortgage, calculate_mortgage_insurance, calculate_loan_early_repayment). The pointer to list_bundles is a discovery cross-reference, not an alternative-selection rule.

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