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

With no annotations at all, the description carries the full burden and does reasonably well: it discloses that the call is paid and the exact price, the on-chain method used (balanceOf), and the shape of the result (raw plus human-readable). It does not cover failure modes (malformed address, non-contract token) or whether human-readable output depends on token decimals.

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?

Three short clauses, front-loaded with the most decision-relevant fact (paid, price), then what it does, then what it returns. Nothing is wasted.

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 two-parameter read tool with full schema coverage and no output schema, the description covers cost, action, and return shape adequately. The remaining gap is edge-case behavior (invalid address, non-ERC-20 contract), which an agent would benefit from knowing before paying for the call.

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 both parameters are already documented as 0x-prefixed token contract and wallet addresses. The description adds no meaning beyond the schema, which is the baseline expectation here.

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?

Names a specific verb and resource ('Get ERC-20 token balance') and pins the mechanism (balanceOf), which cleanly separates it from the native-balance sibling chain_balance. It stops short of explicitly naming that sibling, so the differentiation is implied rather than stated.

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 '$0.0029' cost note is a useful usage signal an agent won't get from annotations, and the ERC-20 scoping implies when to pick this over chain_balance. However, there is no explicit when-to-use/when-not guidance or named alternative.

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