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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses a key behavioral trait: 'Degrades gracefully — any individual call failure returns null for that field.' This is important context for handling partial data and is not captured by the annotations.

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 primary purpose, followed by return details and failure behavior. Every sentence contributes value with no redundancy.

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?

Given the simplicity of the tool (one parameter, no output schema), the description sufficiently covers the return fields and failure behavior. It lists the specific metadata returned and how partial failures are handled, which is adequate for this low-complexity tool.

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?

The input schema already provides a 100% description for the single 'token' parameter ('ERC-20 token contract address'), and the pattern enforces the 0x prefix. The description adds no new semantic meaning beyond the schema, so a 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 verb (Get), resource (ERC-20 token metadata), and scope (a token address on Mezo). It also enumerates the returned fields (name, symbol, decimals, total supply), which distinguishes it from siblings like eth_get_token_info (Ethereum) and mezo_testnet_get_token_info (testnet).

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: use this when you need token metadata for an ERC-20 on Mezo mainnet. However, it does not explicitly mention alternatives or exclusions, such as using mezo_get_token_balance for balances or mezo_testnet_get_token_info for testnet.

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