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

With no annotations, the description carries the burden: it does usefully disclose pricing and that a spot-price USD conversion is performed, which implies a live external price dependency. It does not state that the call is read-only, what happens for an address with zero balance or on an unsupported network, or anything about rate limits/failure modes.

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?

One tight sentence plus a cost prefix; no padding and the resource being read is front-loaded. The price fragment sits first, which is acceptable for a paid endpoint but slightly delays the core purpose.

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, and the description does say what comes back at a high level: the native balance plus its USD value at spot price. Combined with a fully documented 2-param schema, that is nearly complete; only edge-case behavior for unsupported networks or empty balances is missing.

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 description coverage is 100%, so both 'address' (0x-prefixed EVM address) and 'network' (enum with default base) are already documented. The description only adds the note that the native token varies by chain (ETH/POL), which is mild added meaning; baseline 3 applies.

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?

States a specific verb+resource: reads the native-token (ETH/POL) balance of an EVM address and adds a USD spot valuation. It implicitly separates from the sibling chain_token (token balances) because it names 'native-token', but it never explicitly contrasts with that sibling.

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 only guidance is the cost signal ('$0.001 per call'), which implies this is a paid call to be used deliberately. There is no explicit statement of when to pick this over chain_token or chain_networks, nor any prerequisite such as needing a valid address per supported chain.

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