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

Annotations already declare read-only, idempotent, open-world, and non-destructive. The description adds meaningful behavioral context beyond annotations: it requires an API key, uses a weighted unit, computes from 'our pool', and specifies exact response fields per mode. No contradiction.

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?

Though multi-sentence, the description is dense and well-structured: mode definitions first, then use cases, then exclusions, then return shape and auth requirement. Every sentence adds operationally useful information with 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?

For a read-only price tool with no output schema, the description fully equips an agent: required parameters per mode, examples, return fields, auth requirement, and sibling-tool exclusions. Nothing critical for a correct call is missing.

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 baseline is 3. The description adds value by explaining the kind-mode relationship, noting that gas requires a chain and token requires comma-separated symbols, and clarifying that token prices are in USD and gas recommendations are EIP-1559. This goes beyond the schema's terse parameter descriptions.

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 clearly defines two distinct modes ('gas' and 'token') with specific verbs and resources: EIP-1559 gas recommendations and current token prices in USD. It also explicitly names what this tool is not for, distinguishing it from get_quote and list_plans.

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?

Provides explicit when-to-use guidance: before sending a transaction for gas, or to value a balance for token. It also names alternatives (get_quote, list_plans) and explains when not to use this tool.

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