List ERC-20 balances

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

Read-only and idempotent behavior is already covered by annotations, so the description does not need to restate it. It adds a useful behavioral contract by specifying exactly what is returned: token address, symbol, decimals, and balance. It does not discuss pagination limits, but that is a minor gap for this kind of listing tool.

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 two tight sentences: one for the operation and one for the return shape. Nothing is redundant or marketing-heavy, so an agent can parse it quickly.

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 moderate 3-parameter tool with strong annotations and no output schema, the description gives the core information needed to call it: purpose, owner-address parameter, chain context, and return fields. It could mention the default chain_id or pagination behavior, but the input schema already exposes those details.

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 only 33%, and the description partly compensates by clarifying that address is the holder and 'on a chain' scopes chain_id. However, page_size semantics and address format expectations are not elaborated, leaving some parameter meaning to reliance on property names and schema defaults.

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 is specific: 'List all ERC-20 token balances held by an address on a chain.' It names the exact resource type, the required scope/owner, and the return fields, making it immediately distinguishable from generic balance and transaction tools.

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 clearly states when this tool fits: when an agent needs ERC-20 balances for a specific address on a supported chain. It does not explicitly call out native-balance alternatives or say 'use avax_get_balance instead,' so it falls short of full routing guidance.

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