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

Annotations already cover readOnlyHint, idempotentHint, openWorldHint, and non-destructiveness, so the bar is lower. The description adds valuable context beyond annotations: 'Nothing is stored about the customer' discloses privacy/non-persistence, and 'Not an appraisal' clarifies the output's informal status. No contradiction with the annotations.

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?

Three concise sentences with the core purpose front-loaded. Each sentence earns its place: purpose and outputs, formal-appraisal caveat, and privacy guarantee. No filler or redundancy.

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?

Even without an output schema, the description names the expected return components, so the agent knows what it will receive. It does not specify field names, error cases, or fallback behavior when comparables are unavailable, but for a preliminary read-only estimate with safety annotations in place, this 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?

Schema description coverage is only 38%, so the description must compensate. It adds meaning for key parameters indirectly: 'near the customer' clarifies zip, 'odometer-adjusted' clarifies odometer, and 'gap vs the insurer's offer' clarifies acv_offer_cents. However, it does not clarify trim, state, or the required vehicle identifiers beyond what the schema provides, leaving some compensation gap.

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 states a specific verb and resource: 'a no-commitment early market read for a vehicle' and enumerates concrete outputs (10th percentile/median/90th comparable prices, odometer-adjusted mid, gap vs insurer's offer). It also distinguishes itself with 'Not an appraisal' and, given siblings like submit_total_loss_intake and upload_valuation_report, the agent can clearly tell this is the lightweight read-only estimate 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 description clearly positions this as an early, no-commitment read rather than a formal appraisal, giving the agent context for when to invoke it. It does not explicitly name alternatives or state when not to use it, although sibling names such as submit_total_loss_intake make the boundary reasonably inferable.

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