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

Goes well beyond the readOnly/openWorld annotations: it discloses the approximate result count (~18-20), that ordering is Google's, that currency follows the server's region and must be checked in the currency field, that the response confirms the dates Google applied, and the full cost model ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls not charged).

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?

Purpose is front-loaded and every clause carries information (result count, ordering, currency caveat, deal flag, billing). It is a single dense paragraph, so the payment and caveat details are slightly buried at the end rather than separated.

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 read-only, open-world price lookup with an output schema, the description covers the source, result shape, ordering, currency ambiguity, staleness of prices and billing — everything needed to call it correctly and interpret the result.

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 all four parameters are already documented in the schema. The description adds only contextual framing ('city and stay dates') and a note that the response echoes the applied dates; it says nothing extra about limit or date-range constraints, so 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?

States a specific verb and resource — lowest nightly hotel prices for a city and stay dates — and pins the source ('Google Hotels' public results page', Google's ordering and currency), which distinguishes it from sibling hotel aggregators like travel_kayak, travel_trivago and travel_booking_com_hotels.

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?

'Not a booking; prices change constantly' implies the appropriate use (price discovery, not reservation), but the description never names an alternative tool or states the condition under which another hotel source should be preferred. Usage is inferable rather than explicit.

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