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

Annotations already carry the read-only, idempotent, non-destructive hints. The description adds valuable context beyond that: the data source (CoinGecko) and the monetization/pricing model ($0.02 USDC via x402 on Base). This gives the agent useful operational knowledge not present in the annotations.

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 compact and front-loaded with the core purpose. The supported coin list is necessary for the agent to know valid inputs, and the source and pricing info are each one short clause. Every sentence earns its place with no filler or redundancy.

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?

The combination of an output schema (not shown but present) and the annotations already covers return structure and safety. The description fills in the supported universe, data source, and cost model. It could hint at whether prices are live or delayed, but for a simple lookup tool this is adequately complete.

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 schema already fully describes the parameter: the enum lists every supported coin, and the schema-level description gives examples. The main description repeats the supported list verbatim, adding no extra meaning. According to the baseline rule for high schema coverage, a 3 is appropriate.

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 opens with a specific verb ('Returns') and clearly names the resource ('current USD price') along with the exact data fields (price, 24h % change, market cap, 24h volume). The word 'current' distinguishes it from get_crypto_history, and the supported coin list further disambiguates the scope.

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?

The description establishes clear context (current price for a fixed set of supported cryptocurrencies) and implicitly signals this is for current data, not historical. It does not explicitly name alternatives or exclusions such as 'use get_crypto_history for historical data,' so it stops short of a 5.

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