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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses graceful degradation behavior: any individual field call failure returns null for that field. It also clarifies the output includes raw and formatted total supply, adding meaningful behavioral context.

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?

The description is two sentences, front-loaded with the core purpose, and every word earns its place. It clearly states what the tool does, what it returns, and its failure behavior without unnecessary elaboration.

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?

With no output schema, the description fully explains the return values (name, symbol, decimals, total supply) and the failure mode. For a simple one-parameter tool with a clear purpose and network scope, this is complete and self-sufficient.

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% with the token parameter described as 'ERC-20 token contract address' and a 0x pattern. The description adds minimal extra parameter meaning, mainly reinforcing the Ethereum mainnet context. Since the schema already documents the parameter well, the baseline of 3 is appropriate.

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 clearly states the tool gets ERC-20 token metadata for a token address, specifying the exact resource (token metadata) and network (Ethereum mainnet). It distinguishes from siblings like eth_get_token_balance and mezo_get_token_info by explicitly scoping to metadata and Ethereum mainnet.

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 provides clear context: it is for Ethereum mainnet and returns token metadata. It does not explicitly name alternatives or exclusion criteria, but the network and purpose are stated, making it clear when this tool is appropriate relative to testnet or other-network siblings.

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