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

With no annotations, the description carries the full burden. It discloses the payment/auth model (0.005 USDC via x402 or API key) which is valuable context, but it does not explicitly state that the operation is read-only, what the response format looks like, or any rate limits or data freshness characteristics.

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 front-loaded with the core purpose, followed by a concise use-case sentence, and ends with a bracketed access note. Every sentence earns its place with no redundancy.

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 simple no-param read tool with no output schema, the description covers the purpose, use cases, output content (total supply, per-chain breakdown, top stablecoins), and access requirements. It could be slightly more complete by mentioning data freshness or response structure, but it is adequate.

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, so parameter semantics are minimal. The schema is empty and the description does not need to document parameters, meeting the baseline for a no-param tool.

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 states a specific verb+resource ('Global stablecoin metrics') and enumerates the contents: total supply, per-chain breakdown, top stablecoins by market cap. This distinguishes it from most siblings, though it does not explicitly name an alternative like get_global_market or get_market_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?

It gives a clear use case: 'Use it when the user asks about stablecoin supply, USDC or USDT dominance, or overall market liquidity.' However, it does not specify when NOT to use it or name a sibling tool that should be used instead.

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