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

Goes well past the readOnlyHint/openWorldHint annotations: discloses the upstream source (rbauction.com public auctions page), the residential-proxy retrieval path, the exact price ($0.002 USDC per successful call), accepted payment rails (x402 on Base, Solana or Arc), and that failed calls are not charged. That operational and billing context is exactly what annotations cannot convey.

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 sentences, front-loaded with the source and payload, then the filtering and payment facts. The first sentence is a long comma-separated field list that reads as a run-on, but no sentence is wasted; the pricing/proxy detail earns its place.

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?

An output schema exists, so return-shape explanation is not required, yet the description still sketches the payload; both parameters are covered by schema; and the payment, sourcing, and failure semantics are all stated. Nothing an agent needs to call this correctly 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?

Schema description coverage is 100%, so both `limit` and `country` are already documented in structured form. The description restates the same ISO-3 example set and the filter concept without adding syntax, defaults, or edge-case behavior beyond the schema — baseline 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?

Names a specific source and resource — the Ritchie Bros. (rbauction.com) auction calendar — and enumerates the domain ('heavy-equipment, truck and agriculture auctions') plus the returned fields. That specificity separates it from the other auction-adjacent sibling (travel_bringatrailer_auctions, which is vehicles) without opening a schema.

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?

Usage is only implied: 'Filter by country code (ISO-3) and limit' tells the agent how to narrow results but never states when this tool is the right choice versus alternatives, nor any prerequisite or exclusion. No alternative tool or 'use X instead when…' routing is provided.

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