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

Annotations already declare readOnly and openWorld, so the safety profile is covered. The description adds genuinely useful non-structural context: per-call cost ($0.002 USDC via x402 on Base/Solana/Arc) and that failed calls are free, which materially affects invocation decisions.

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-loads what data is returned, then the parameter range, then payment terms – three tight sentences with no filler. Every sentence carries distinct, decision-relevant information.

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?

With an output schema present, return values needn't be explained, yet the field list still helps. The lone parameter and annotation-based safety profile are well covered; only the lack of sibling routing guidance leaves a minor gap.

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?

Schema coverage is 100%, so the single 'limit' parameter is fully documented in the schema. The description's 'N from 1 to 100' restates the schema's bound rather than adding new semantics, so the baseline of 3 applies.

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 verb: CoinPaprika top crypto tickers by market rank, enumerating the exact metrics (USD price, 24h volume, market cap, 1h/24h/7d changes). The 'CoinPaprika' source distinguishes it from siblings like finance_coingecko and finance_coinmarketcap that return similar 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?

Clarifies the scope ('first N coins by rank, N from 1 to 100'), which implies it's a ranked-list tool rather than a lookup. However, it never says when to choose it over the many sibling ticker/market tools, leaving alternative selection to inference.

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