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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses significant behavioral details: it uses simulated gas, current token prices, fresh chain heads, and rollup L1 fees; it excludes unmeasurable chains rather than estimating them; it orders results cheapest first; and it mentions pricing and terms. No contradiction with annotations. This is rich, helpful context.

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 somewhat long but well-structured, with each sentence contributing distinct information: methodology, output characteristics, exclusion behavior, terms, and pricing. It front-loads the core purpose and avoids fluff. Slightly verbose due to pricing/terms, but acceptable for a paid tool.

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?

There is no output schema, so the description must explain the return format. It says 'Inputs and block references accompany each figure' and 'cheapest first,' but it does not specify whether the output is a list of objects, units, or exact fields. While the overall behavior is clear, the lack of explicit output structure leaves some ambiguity for an agent.

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 only parameter 'chains' is fully described in the schema with a comma-separated list and default behavior. The description reiterates the chain names and adds the output ordering (cheapest first), but does not add additional meaning to the parameter itself. With 100% schema coverage, the baseline of 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 clearly states the tool measures USDC transfer costs across five named chains, with specific details on methodology (simulated gas, token prices, chain heads, rollup L1 fees). It also distinguishes from siblings by noting it provides a comparison ('cheapest first') rather than just identifying the cheapest chain, as implied by the sibling 'cheapest_settlement_chain'.

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 gives clear context on what the tool does and its scope, but does not explicitly state when to use it over alternatives like 'cheapest_settlement_chain' or when not to use it. The business/professional use note and pricing provide usage conditions, but no direct comparison to siblings. The context is clear, but exclusions/alternatives are absent.

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