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

The description adds significant behavioral context beyond the readOnlyHint and openWorldHint annotations: it discloses the specific return fields and the graceful degradation behavior where individual field failures return null. This is particularly useful because it sets expectations for partial failures, which is not evident from annotations alone.

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 concise sentences, front-loaded with the primary purpose, followed by return data and a key behavioral note about graceful degradation. Every word adds value, with no fluff or repetition.

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 simple single-parameter read-only tool, the description is complete: it states the input, the output fields, and the edge-case behavior (per-field null on failure). Without an output schema, listing the return fields is essential and adequately covers expected results. The network specificity also addresses the testnet context.

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 sole parameter 'token' clearly described as 'ERC-20 token contract address'. The description merely echoes this by saying 'token address' but adds no new semantic detail; it relies on the schema for parameter 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 clearly states the action ('Get ERC-20 token metadata') and the specific resource ('a token address on Mezo testnet'), and it distinguishes from siblings by specifying the network and token standard. It also lists the exact return fields (name, symbol, decimals, total supply), leaving no ambiguity about the tool's function.

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 implies usage context by targeting 'Mezo testnet' and ERC-20 tokens, but it does not explicitly state when to prefer this tool over alternatives like mezo_get_token_info or eth_get_token_info. There are no exclusions or alternative recommendations, so the guidance is only implied.

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