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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond those hints: that the call is free, makes no network request, and requires no payment — which explains why a pricing tool exists in a payment-gated toolset.

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 short sentences, zero filler, and the most decision-relevant fact ('Free') is front-loaded before the return-field list. Every clause 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?

There is no output schema, so the description compensates well by enumerating the returned fields. It stops short of describing the shape or currency of the price values, a minor gap for an otherwise complete zero-argument definition.

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?

With zero parameters there is nothing for the schema to document beyond an empty object, so the baseline is 4. The description reinforces this explicitly with 'No input', removing any doubt about required arguments.

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 ('Return') and resource ('the price of every paid tool'), then enumerates the exact fields returned (payment network, receiving address, data source). The four sibling tools are all vendor/status oriented, so there is no ambiguity about which tool to pick for pricing data.

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 text signals applicability indirectly ('Free', 'No input, no network request, no payment'), which tells the agent this is a zero-cost, zero-argument lookup. It never states when to choose this over alternatives or what conditions select it, so usage is only implied.

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