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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description adds substantial behavioral detail: how sale estimates are derived ('verified sales, or the asking band scaled by a measured clearance ratio; basis labeled'), that multiple configurations may be returned, and how the aggregate estimate collapses to a single mid or a low-to-high range depending on ambiguity. This goes well beyond the annotation scaffolding.

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 dense but every sentence earns its place: purpose, examples, return contents, estimate methodology, ambiguity handling, and usage guidance. It is front-loaded with the core 'what a used Mac is worth' statement and then layers in necessary detail without fluff.

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?

There is no output schema, so the description carries the full burden of explaining return values. It does so thoroughly: configurations, sale estimate with basis, live asking band, aggregate single-mid vs low-to-high range, and the sale-vs-asking distinction. Nothing needed to call or interpret the tool is 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?

The schema already documents the single model parameter at 100% coverage, including format and examples. The description contributes further example strings and notes that Apple's name may leave the chip open, but this is incremental rather than essential, so the baseline score of 3 applies.

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 opens with 'What a used Mac is worth, from the name Apple gives the model' and then specifies exactly what is returned: configurations, sale estimates, and asking bands. It clearly identifies the resource (Mac market value) and the verb (get/return), and the Apple Silicon scope helps separate it from sibling tools like lookup_mac_serial and check_mac_listing.

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 gives clear when-to-use context by limiting the tool to 'Apple Silicon Macs only' and instructs the agent to 'Use the sale estimate as the price of the Mac; asking is seller guidance.' It does not explicitly name alternative tools or contrast with siblings, so it falls just short of a 5.

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