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

With no annotations present, the description carries the load and does meaningful work: it discloses the payment cost ($0.005 USDC on Base via x402), that data is read live from OP Mainnet, and that only explicitly listed tokens are returned (no auto-discovery). It stops short of covering failure modes such as invalid or non-ERC-20 token addresses.

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?

A single dense sentence with the core capability front-loaded and the cost/chain constraints trailing. Every clause contributes something an agent could not infer from the schema alone.

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, so the description correctly explains the return shape (balances formatted with symbol and decimals) and the payment requirement. That covers what an agent needs to call it, though error handling for malformed or non-ERC-20 token entries is left unstated.

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 in the schema. The description restates the 20-token cap and the ERC-20 nature of the listed tokens but adds no syntax, ordering, or edge-case detail beyond what the schema provides, so 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?

The description names a specific resource (native ETH plus up to 20 listed ERC-20 balances) on a specific chain (OP Mainnet), so the verb and scope are unambiguous. It does not explicitly separate itself from the near-identical sibling optimism_wallet_profile or optimism_token_snapshot, which keeps it from a 5.

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?

Usage is implied by the phrasing 'tokens you list' and 'read live from OP Mainnet', which suggests a spot-check read. There is no explicit when-to-use guidance, no statement of when to prefer optimism_wallet_profile or optimism_token_snapshot, and no preconditions beyond the address.

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