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

With no annotations, the description carries the full burden of behavioral disclosure. It helpfully reveals that the tool costs 0.01 USDC on Base via x402, or 12 sats Cashu ecash or Lightning, which is important for an agent to know before invoking. However, it does not discuss rate limits, error handling, response format, or whether the operation is read-only, leaving significant behavioral gaps.

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 tool's purpose and data fields, followed by payment details. It uses two sentences with no obvious filler, though the payment enumeration is lengthy. Every sentence contributes relevant information, but the structure could be slightly tighter.

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?

Given no annotations, no output schema, and 0% schema coverage, the description should be more complete. It covers the main data fields and coin id format, and it adds payment costs, but it omits the 'vs' parameter entirely and does not describe the shape of the response or any error conditions.

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 0%, so the description must compensate for both parameters. It explains that 'ids' takes comma-separated coin ids and gives examples, which is useful. But it never mentions the 'vs' parameter at all, leaving half of the inputs undocumented and likely ambiguous for an agent.

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 resource and source: 'Crypto prices from CoinGecko' and lists the exact data fields (price, 24h change, market cap and volume). It also names the input format for coin ids, making the tool's scope clear. However, it does not differentiate itself from similar siblings like btc_snapshot or fx_rates, so it falls short of a 5.

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?

There is no explicit guidance on when to use this tool versus alternatives such as btc_snapshot or fx_rates. The description only implies usage by saying what data it returns, offering no when/when-not conditions or preferred contexts.

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