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

Beyond the readOnlyHint annotation, the description discloses important behavioral constraints: native ETH only, Ethereum mainnet and Base only, EIP-55 checksummed address requirement, and block-accurate on-chain exactness. This gives the agent safety and compatibility information that annotations alone do not provide.

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 heading-based structure is clear and front-loaded, but there is some redundancy: the fact that get_wallet_portfolio already includes native ETH appears twice, and 'Use when:' is followed by 'Use when'. Minor repetition keeps it from being a 5.

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 two-parameter read-only tool with an output schema present, the description covers purpose, usage timing, limitations, and alternatives. Nothing essential is missing for an agent to decide whether to call this tool and do so 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 the baseline is 3, but the description adds meaningful parameter context by requiring an EIP-55 checksummed address and clarifying chain support (Ethereum vs Base). It also explains the output units in wei and ether, which helps the agent interpret results.

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 verb and resource: getting the exact on-chain native ETH balance of an address on Ethereum or Base, in wei and ether. It explicitly distinguishes itself from get_wallet_portfolio and get_erc20_balance, so an agent can immediately tell which tool fills this niche.

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?

It gives explicit when-to-use guidance for gas-availability checks and standalone balance verification, and clearly instructs not to call it after or alongside get_wallet_portfolio. It also names the alternative tools for portfolio and ERC-20 balances.

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