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

With no annotations, the description carries the burden and does disclose key traits: it is a live on-chain read, the response is human-formatted with symbol and decimals, the token list is capped at 20, and it costs $0.005 USDC on Base via x402 — a non-obvious payment prerequisite. It omits failure behavior for invalid/unverified token contracts and any rate-limit or caching behavior.

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?

Two dense sentences with zero filler: output shape and scope first, then cost and provenance. Every clause carries information an agent needs.

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 no output schema, the description usefully specifies the return shape (symbol and decimals per token) and the payment model. The remaining gap is how unlisted or invalid token addresses are handled.

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 only restates the 'up to 20 ERC-20 tokens you list' constraint. Baseline 3 is appropriate since the schema does the heavy lifting and the description adds no syntax or format detail beyond it.

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 native POL plus listed ERC-20 balances on Polygon PoS, with symbol/decimals formatting. An agent can tell this returns balances rather than a profile or allowance. It does not explicitly contrast with polygon_wallet_profile or polygon_erc20_allowance, which are the closest siblings.

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 resource name and chain, but there is no explicit when-to-use / when-not statement and no alternative named. An agent must infer that this is the tool for balances and that polygon_erc20_allowance covers approvals instead.

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