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

Annotations already declare readOnlyHint and openWorldHint, so the agent knows it is a safe read operation. The description adds valuable context beyond this: the interpretation of the premium sign, the cost per call, the payment method (x402), and the required client SDKs. This provides meaningful behavioral/transactional transparency.

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 well-structured: the core purpose is front-loaded, followed by the interpretation of the output, and then cost/payment details in a clean bulleted format. Each line earns its place, though there are more sentences than the minimal ideal. It is concise without being terse.

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 parameterless, read-only tool, the description is exceptionally complete. It explains what the metric means, how to interpret positive/negative values, how it differs from Kimchi Premium, and adds critical operational details (cost, payment method, client options, docs). Given an output schema exists, the description does not need to explain return values. This fully equips the agent to decide when and how to invoke it.

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 input schema has zero parameters, so there is no parameter detail to clarify. The baseline for zero parameters is 4, and the description adds useful context about the underlying data source (Korean exchanges, official USD/KRW rate), though this is not strictly parameter semantics. It is adequate given the schema already conveys everything about parameters.

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 what the tool does: 'Get USDT and USDC premium on Korean exchanges vs official USD/KRW rate.' It also explains the meaning of positive/negative premium and explicitly distinguishes this tool from Kimchi Premium, differentiating it from its sibling tool 'get_kimchi_premium'.

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 clear context for use: it is a 'key indicator of Korean market fund flow direction' and explicitly notes it is 'separate from Kimchi Premium,' giving the agent a basis for choosing this tool over alternatives. However, it does not explicitly name or exclude the alternative tool for Kimchi Premium, so it falls short of a full when-to-use/alternatives specification.

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