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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds that it returns an 'Estimate' (non-binding flavor) and the exact return keys, but the return keys duplicate the existing output schema, leaving limited extra behavioral context.

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 tight sentences that front-load the purpose, then the return shape and related-tool pointer. Little wasted text, though restating the return keys is slightly redundant given the output schema.

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?

Inputs, output shape and a related-tool pointer are all present, and annotations plus the output schema cover safety and return details. Only a note about the estimate being non-binding/indicative is arguably 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 description coverage is 100%, so the schema already documents all three parameters including the bonus-malus range (0.5=best, 3.5=worst) and defaults. The description merely lists them, adding no syntax or unit detail beyond the 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?

Specific verb 'Estimate' combined with a precise resource 'annual car insurance' and the three driving inputs. This clearly separates it from generic insurance siblings like calculate_travel_insurance_estimate or calculate_mortgage_insurance, though it never explicitly names a competing tool.

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 pointer to 'See list_bundles for related auto-transport calculators' gives a discovery path but is not a when-to-use/when-not rule. There are no explicit prerequisites or exclusions, so usage is only implied by the resource name.

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