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

With no annotations, the description carries the full burden, and it does disclose two valuable non-obvious traits: the data source (CoinGecko) and a per-call cost of 0.001 USDC via x402 on Base, which affects whether an agent should call it at all. It omits error behavior for invalid ids, data freshness/latency, and whether an empty ids list returns anything, which matter for an unannotated tool.

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?

Three tight sentences: what it returns, when to use it, what it costs. The most decision-relevant facts are front-loaded and nothing is padding.

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 2-param read tool with no output schema this covers the essentials, and mentioning 24h change and market cap usefully signals the return shape. However, all params are optional in the schema while the description says "one or more ids", and it never says what happens if ids or vs are omitted, which leaves a real calling ambiguity unresolved.

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 the baseline is 3. The description adds illustrative id values (bitcoin, ethereum, solana) and pins the unit to USD, but never explains the `vs` parameter as the override for that currency, leaving its role only implied by the schema example.

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 (crypto/token price in USD with 24h change and market cap) sourced from CoinGecko ids, so an agent knows exactly what data comes back. It does not explicitly distinguish itself from the sibling dex_quote, which is the nearest conceptual neighbour for price-related needs, but the resource itself is unambiguous.

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?

Gives explicit usage context: "Use it when an agent needs a current price before quoting or sizing a trade." That routes the agent well for the common case. It stops short of exclusions or naming alternatives, so the boundary with dex_quote (spot price vs executable swap quote) is left to inference.

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