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

Annotations already declare this is read-only, idempotent, non-destructive, and not open-world. The description adds meaningful operational context beyond annotations: data source is CoinGecko, prices are at most about 60 seconds old, and only top-100 coins are covered.

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 resource and return fields, then immediately explains the two calling modes. Every sentence contributes useful information, and there is no filler.

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?

Although there is no output schema, the description enumerates the returned fields and data freshness. With annotations covering safety and the schema covering parameters, an agent has everything needed to invoke this tool correctly.

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 description coverage is 100%, so both `limit` and `symbols` are already documented in the schema. The description reinforces that symbols accept tickers, CoinGecko ids, or names, and that omission returns the top N, but adds little beyond the structured parameter documentation.

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 and resource: live USD prices for the top 100 cryptocurrencies by market cap, including the exact fields returned. Sibling tools are about ZEC ETF history and signals, so this tool is clearly distinguishable as crypto spot pricing rather than ETF 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 explicitly explains when to pass `symbols` for specific coins versus omitting them for the top N by market cap. It also states the boundary condition that coins outside the top 100 are not available, which prevents incorrect calls.

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