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

Annotations already indicate a read-only, idempotent, non-destructive operation. The description adds meaningful context beyond annotations: the price is indicative, sourced from routed liquidity, free of service fees, and not an oracle quote. This gives an agent a realistic sense of the result's nature, though it does not mention rate limits or availability.

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 three short blocks with no filler. The first sentence front-loads the core purpose, and each subsequent sentence adds a distinct, useful detail about pricing source, fees, and transaction effects.

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 simple read tool with an output schema and strong safety annotations, the description adequately covers purpose, price source, and fee context. However, the lack of explanation for chain, amount, and caller_id is a notable gap given the schema itself provides no descriptions, leaving part of the invocation surface ambiguous.

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?

With 0% schema description coverage, the description must compensate, but it only adds clarity for token_address and quote_token (default USDC), and only indirectly for amount via 'what one whole token sells for'. The parameters chain, amount, and caller_id are left underspecified, leaving an agent to guess their accepted values and behavior.

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 ('an ERC-20 token on an EVM chain') and the action (returning an indicative price), and clarifies it is priced via 0x rather than an oracle. This distinguishes it from tools like token_info and verify_token, though it lacks an explicit verb and does not differentiate it from evm_swap_quote.

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 implies when to use it: when you need a routed-liquidity indicative price, not an oracle price, and when you want a free read with no transaction notional. It does not explicitly name any alternative tools or state when not to use this tool, so guidance is inferred rather than explicit.

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