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

Annotations already declare readOnly, idempotent and closed-world, so the safety profile is covered. The description adds real value beyond them: the returned band structure, an attached method and confidence, and a disclaimer that this is not a formal appraisal — a material behavioral/legal constraint the annotations cannot express.

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, front-loaded with what the tool returns and followed by the accepted input combinations. No filler or repeated schema content.

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?

For a seven-parameter, all-optional estimation tool with no output schema, the description covers output shape, input alternatives and scope limitations well. It does not say what happens when no valid input combination is supplied (error vs. degraded estimate), which is the remaining gap.

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 each parameter is already labeled, giving a baseline of 3. The description goes further by stating the alternative OR-combinations of parameters, which the schema (all optional, zero required) cannot convey on its own.

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 names a specific verb and resource ("used-boat value estimate") and even previews the output shape (low/mid/high band with method + confidence). It is distinguishable from siblings such as estimate_total_cost_of_ownership, though it never names them explicitly.

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?

It gives concrete invocation paths — modelId, or make+model+year, or loaFt+boatType, or a HIN — which tells the agent how to call it with whatever data is on hand. It adds a scope caveat ("Educational, not an appraisal") but offers no explicit when-not-to-use or sibling routing.

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