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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds that the call is free and enumerates the returned fields, which partially compensates for the absent output schema, but says nothing about output format, units, or freshness of the terms.

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 fragments, front-loaded with the key fact ('FREE') that an agent decides on. It is terse to the point of being clipped, but no sentence is wasted.

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 zero-arg read-only tool the description covers the essentials — cost and returned fields — especially with no output schema. It still leaves ambiguous whether the returned 'how to pay' is instructions versus a transaction object, and whether the terms are static or per-request.

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?

The tool takes zero parameters, so the baseline is 4; the schema adds nothing and the description correctly implies no inputs are needed.

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?

The description names what information is returned (price, recipient, network, asset, payment method) and ties it to the sibling scan_solidity_full, which is useful. However there is no verb stating what the tool actually does (e.g., 'returns payment details'), so the agent must infer that calling it yields those fields.

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?

'FREE' signals there is no cost to calling it, and naming scan_solidity_full implies this is a prerequisite lookup for that tool. But the relationship is only implied — there is no explicit 'call this before invoking scan_solidity_full' or exclusion of when not to call it.

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