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

With no annotations, the description carries the full load, and it does disclose useful behavior: it is an eth_call read, it returns formatted total_supply plus symbol and decimals, and it costs $0.001 USDC. It omits failure behavior for non-contract addresses or unsupported chains and does not say whether results are cached or how decimals are applied when the call reverts.

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?

One compact sentence plus a single example and price line; the purpose is front-loaded, the example doubles as format documentation, and nothing is redundant.

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?

No output schema exists, but the description enumerates the return fields (total_supply, symbol, decimals), so return shape is covered. The remaining gaps are the default for the optional chain parameter and behavior on invalid or non-token addresses, which are minor but real for a financial-data call.

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 0%, so the description must compensate, and it partially does: the example shows token as a 0x address and chain as a chain-name string like "base", clarifying format beyond the bare string types. It never explains that chain is optional or what default applies when it is omitted, which is the most consequential ambiguity for a 2-parameter tool.

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 verb and resource ("Total supply of an ERC20 or ERC721 token") and even the underlying mechanism (totalSupply via eth_call), which clearly separates it from siblings like chain_erc20_balance or token_metadata. It stops short of explicitly naming those siblings, so an agent must infer the boundary rather than being routed.

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 only implied: the worked example shows a concrete invocation and the mention of totalSupply hints at the read path, but there is no explicit "use this when…" statement, no exclusions (e.g., use token_metadata for decimals/symbol alone), and no note on prerequisites such as the token being a contract.

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