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

Annotations only include readOnlyHint, so the description carries the burden of behavioral disclosure. It discloses the output format (normalized by decimals, symbol), the limitation of one token per call, the need for a contract address (no symbol lookup), and the lack of USD valuation. It does not contradict the readOnlyHint. Slightly more could be said about error handling, but the core behavior is well covered.

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 structured into sections (purpose, use when, limitations, alternatives) and front-loads the core function. While it's longer than a single sentence, each section adds distinct value and there is no redundancy. It earns its length without being verbose.

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 tool with an output schema and 100% parameter coverage, the description covers the key operational context: when to use, limitations, and output characteristics. It does not mention potential error conditions or rate limits, but for a simple balance check, these are minor. The description is sufficiently complete for an agent to call it correctly.

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 parameters are already documented. The description adds the clarification that token_address must be a contract address and cannot be a symbol, and mentions the supported chains (Ethereum/Base). This is a modest enhancement over the schema, which already labels the token_address as a contract address. Baseline 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 verb (Get), the resource (on-chain ERC-20 balance of a wallet for one token contract), and adds specific detail (normalized by decimals, returned with symbol). It explicitly differentiates from sibling tools like get_wallet_portfolio (multi-asset) and get_eth_balance (ETH), so an agent can select it correctly.

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 'Use when' guidance with a concrete example (confirming funds before approval/transfer), explicitly says when not to use it (multi-asset portfolio → get_wallet_portfolio), and lists alternatives at the end. This is fully actionable.

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