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

Annotations already declare readOnlyHint and destructiveHint=false, but the description adds value beyond them: a non-ERC-20 address returns 422 uncharged, failed calls are free, and each successful call is billed ($0.01, x402 USDC or card key, first 25 free). That pricing and error behavior is unavailable in any structured field and directly affects invocation strategy.

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?

Purpose is front-loaded in the first clause and each subsequent sentence carries distinct information (use cases, alternative, input form, error behavior, pricing). The pricing sentence is dense and could be tightened, but nothing is redundant filler.

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 one-parameter read tool with no output schema, the description enumerates the exact returned fields (name, symbol, decimals, total supply) and covers cost, failure mode, and alternatives. 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 already documents the ticker-or-0x-address duality, so the description's restatement adds little on its own. It does add a worked example address and the failure semantics for a bad address, which go slightly beyond the schema, but ticker resolution behavior (e.g., ambiguity) is not elaborated.

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 (look up name, symbol, decimals, total supply of an ERC-20 token contract on Sonic) and explicitly delineates the scope as 'live from the contract.' It also names the sibling it is not (sonic_token_balance), so an agent can discriminate without opening either 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 two concrete use cases (identifying an unknown token address, formatting raw amounts) and an explicit exclusion routing holder balances to sonic_token_balance. The when/when-not pair is stated, not inferred.

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