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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds the fact that the tool is free and reports pricing, which is useful but not deeply behavioral. With annotations providing the core transparency, a score of 3 is appropriate.

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?

The description is concise, two sentences, with the key information front-loaded: 'FREE' and the coverage list. The standalone 'FREE.' is slightly awkward but not wasteful. Every word earns its place, and the external link is relevant. It loses a point for the fragmented opening, but is otherwise tight.

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?

Given the tool has no parameters, no output schema, and strong annotations, the description covers the essential purpose and even adds the pricing link. It could benefit from stating the return format (e.g., a list of assets), but for a simple free listing tool, this is nearly complete. The annotations and simple nature lower the required richness.

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 has zero parameters, and the schema description coverage is 100% (vacuously). With no parameters to document, the baseline is 4. The description does not need to add parameter meaning and does not, which is acceptable.

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 clearly states the tool reports which crypto assets, venues, operators, and modes the settlement oracle supports, plus pricing. The verb is implied by the name ('list') and the description uses 'which...supports' to convey the listing action. It distinguishes from sibling tools by focusing on settlement oracle coverage, though it does not explicitly contrast with list_jurisdictions.

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 provides minimal usage context: it marks the tool as 'FREE' and points to a paid human-facing pricing page, implying this is the free tier. However, it gives no explicit when-to-use guidance, nor does it mention alternatives like list_jurisdictions for jurisdiction-specific coverage. The link to paid feeds is a distinction but not a clear usage rule.

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