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

Annotations declare readOnlyHint and openWorldHint, but the description adds critical context beyond them: bidder identities are not returned, and calls are metered at $0.002 in USDC via x402 across Base, Solana or Arc, with failed calls uncharged. That payment/auth disclosure is exactly the kind of operational detail an agent needs before invoking.

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?

It is a single dense paragraph but front-loads the core purpose and resource before the return fields and pricing. Nothing is filler, though the run-on sentence is a bit compressed for the amount of information carried.

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 four-parameter read-only tool with an output schema and full annotation coverage, the description covers scope, per-lot return fields, total matching lots, exclusions and billing. An agent has enough to select and invoke it correctly without opening the schema.

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 coverage is 100%, so the baseline is 3. The description adds real meaning for the `status` parameter by explaining that 'upcoming' returns current bid, bid count, estimate range and sale type while 'past' returns hammer price, which the schema only labels 'upcoming (default) or past'.

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?

States a specific verb and resource: auction lots from Invaluable for a keyword, with an explicit upcoming vs past split. It is clearly distinguishable from the ecommerce product-search siblings because it is a keyword search over auction lots rather than retail catalogs.

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 makes the intended use clear: pass a keyword and choose 'upcoming' for lots with current bid, or 'past' for hammer price results. It does not name an alternative tool or a when-not condition, so it earns 4 rather than 5.

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