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

Annotations already declare readOnly/destructive/openWorld, so the safety profile is covered; the description still adds real value by disclosing the cost model ($0.01/call via x402 or card key, first 25 free, failed calls free, repeats are not free), which explains why idempotentHint is false. It also states data is read live from the contract. It does not cover rate limits or what happens for an unrecognized ticker.

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 front-loaded sentences with no filler: scope/returns first, then inputs and use case, then cost and safety. It is dense but each sentence carries distinct information; the 'Example: token=USDC' fragment is the only near-redundant piece.

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-only tool with no output schema, the description covers inputs (address or ticker, chain choices), return contents, cost implications and side-effect profile. Nothing an agent needs to call it correctly 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 coverage is 100% and the chain enum-like list is documented there, so the baseline is 3. The description adds meaning by naming accepted ticker forms (USDC, USDT, WETH, DAI…) and giving a concrete call example, which reduces malformed input more than the schema alone would.

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 and resource (total supply of any ERC-20), enumerates the supported chains, and lists exactly what is returned (raw and decimal-adjusted supply, decimals, name, symbol). An agent can distinguish this from price/token-info siblings without opening the schema.

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?

Gives explicit when-to-use framing: 'Use to check a token's circulating maximum or compare supply across chains,' plus an input example. It does not name a when-not-to-use case or point at alternatives such as token_info, price_token or stablecoin_supply, which would be needed for a 5.

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