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

Annotations already declare readOnlyHint and idempotentHint, and the description adds valuable behavioral context beyond them: it returns both raw and formatted values, resolves decimals on-chain with labeled fallbacks, and preflights so the caller never pays during an RPC outage. This meaningfully helps an agent predict 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 carry all key information: scope, return nature, decimals handling, and the preflight guarantee. Information is front-loaded and no words are 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 read-only, idempotent tool with a full input schema and an output schema present, the description covers the essential behavioral details: raw/formatted output, decimal resolution fallback, and preflight safety. 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 description coverage is 100%, so the schema already documents all three parameters including the decimals override behavior. The description's mention of on-chain decimals and fallbacks mostly restates the schema, adding little new parameter-level meaning.

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 unambiguously identifies an ERC-20 balanceOf read for an address at a token contract, and the ERC-20 scope clearly distinguishes it from sibling balance_check. However, it lacks an explicit imperative verb such as 'Retrieves' or 'Returns', so it just misses the top rating.

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 description gives clear context: use this for raw and formatted ERC-20 balances at arbitrary token contracts, with a practical preflight guarantee. It does not explicitly state when NOT to use it or name alternatives like balance_check, so it stops short of a full 5.

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