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

Annotations already cover safety profile (readOnly, idempotent, openWorld, non-destructive), and the description adds substantial context beyond them: pricing ($0.01/call over x402), the prepaid x-credit-token unlimited option, 1 free call/day, and no API key required. It doesn't describe the response shape, but an output schema exists, so this is strong value-add.

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?

Front-loaded with the resource and ranking details, and the pricing/access info is useful rather than filler. It opens with slightly redundant framing ('What the market is watching right now — global attention feed — The coins most searched...'), but overall it is efficient and 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?

For a zero-parameter read tool with an existing output schema, the description covers purpose, differentiation from the sibling, safety caveats, and payment/auth mechanics. Nothing an agent needs to invoke it correctly is missing.

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 there are no parameter semantics to document; the baseline of 4 applies. The description correctly implies a simple no-argument call with no filtering options.

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 resource and scope: 'coins most searched on CoinGecko right now, ranked, with market-cap rank, price and 24h change.' It also explicitly distinguishes itself from the sibling trending-tokens by noting it is a global feed while trending-tokens is Base-DEX specific, so an agent can route without opening either schema.

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?

Names the alternative (trending-tokens) and the selecting condition (Base-DEX specific vs global). It also states when NOT to trust the output ('attention signal, not quality or safety') and points to token-risk for vetting, giving explicit use and exclusion guidance.

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