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

Beyond the readOnly/destructive annotations, the description discloses the single-supported-product limitation, the fixed price (EUR 39), the meaning of the isWaivedForCaller return value, the automatic waiver behavior, and the required NOMADSTAYS_MCP_AGENT_TOKEN. That is substantial behavioral context the annotations do not carry.

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?

Three tight sentences with zero filler; the highest-value fact (only product 8 is supported) and the return-value semantics are front-loaded. Every sentence 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?

With annotations covering the read-only safety profile and no output schema present, the description fully compensates by explaining the return value, the waiver outcome, the product limitation, and the auth requirement. Nothing needed to call it 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% and the schema already tells the caller to use 8 for the Stay Application fee. The description only adds the EUR 39 value, which is useful but marginal beyond the structured field, so the 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+resource ('Look up a Nomad Stays product's price and purchasability') and narrows scope immediately ('currently only product 8, the Stay Application fee'). An agent can distinguish this from sibling read tools like getPurchaseStatus and from the purchaseProduct mutation.

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 frames the follow-up path clearly: if isWaivedForCaller is true, 'there's nothing to pay and purchaseProduct will process the waiver automatically', which routes the agent to the correct next tool. It stops short of an explicit when-to-use/when-not statement or naming alternative tools directly, but the context is unambiguous.

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