credit_card_coverage

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds context about the two query modes and the return structure (coverage type, max days, summary). However, it does not disclose edge cases like what happens if no coverage is found or if the card is unrecognized. Since annotations carry the read-only signal, a slight gap remains.

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 description is front-loaded with the purpose, followed by usage instructions and return values, in three short paragraphs. Every sentence serves a clear purpose with no wasted words.

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?

The tool has an output schema (not shown but mentioned), so the description's brief return summary is acceptable. It covers the core functionality but could mention error handling or what happens with invalid inputs. Given low complexity, it is nearly complete.

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 input schema has 0% description coverage for parameters. The description fully compensates by explaining each parameter's semantics: 'credit_card_product_name' is the exact product name, 'card_number_bin' is the first 6-8 digits, 'card_provider' is the network, and it clarifies the required combination. This adds essential meaning beyond the raw schema.

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 clearly states the tool's action: 'Look up rental car CDW/LDW coverage provided by a credit card.' It uses a specific verb ('look up') and resource (credit card coverage), which distinguishes it from sibling tools like search_vehicles or get_vehicle_booking_coverage.

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 description explicitly tells when to use each parameter set: 'Provide EITHER credit_card_product_name OR card_number_bin + card_provider.' It also specifies the exact values for card_provider ('visa', 'mastercard', 'amex', or 'discover') and the BIN format ('First 6-8 digits'). This provides clear guidance for correct invocation.

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