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

Annotations already declare the call read-only, idempotent, and non-destructive. The description adds genuinely useful behavioral context beyond those annotations: each sub-call tolerates a token that does not implement it (no revert), the call costs $0.001 USDC, and the output is byte-identical to a specific REST endpoint. There is no contradiction with the annotation hints.

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 dense and efficient: purpose in one clause, cost in the next, supported chains, then endpoint equivalence. There is no filler, although the byte-identical example URL is fairly long; it still serves as an unambiguous reference. The structure front-loads the core purpose before the cost and chains details.

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?

Because an output schema exists, the description does not need to explain return values, and it covers the essential decision factors: what the call aggregates, how much it costs, which chains are supported, and that it tolerates missing token methods. The only notable gap is the lack of explicit guidance about choosing between this and time/block-specific variants, but overall it is complete for a read-only tool.

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 input schema already documents both parameters with 100% coverage, including the list of valid chain keys and the token address requirement. The description only repeats the chain list and adds no new meaning or format details for the parameters. Baseline 3 is appropriate since the schema does the heavy lifting.

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 identifies the tool as aggregating 'the four ERC-20 view calls a listing needs,' and the title confirms those are name, symbol, decimals, and supply. This clearly conveys the resource and output, and the ERC-20 qualifier distinguishes it from NFT metadata and balance tools. However, it lacks an explicit verb like 'returns' and does not distinguish itself from the closely named sibling chain_token_meta_at.

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 provides one usage context ('a listing needs'), specifies cost, and lists supported chains, which helps an agent understand when it is appropriate. It never explicitly states when to prefer this over siblings such as chain_token_meta_at or chain_token_balance, nor does it give when-not-to-use guidance. The usage cue is implied rather than directly stated.

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