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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds significant value by stating a per-call cost, listing supported chains, and explaining the mechanism (via supportsInterface). It also mentions it's byte-identical to a specific GET endpoint, which adds operational detail beyond 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 only two sentences, yet packs in purpose, cost, supported chains, and an exact endpoint reference. Every sentence contributes, and the key information is front-loaded. There is no fluff.

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 tool with only two parameters and an output schema, the description covers the essential aspects: what it returns, cost, chains, and an exact API mapping. It also distinguishes from siblings by describing its specific function. Nothing critical is missing for an agent to decide whether and how to call it.

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 describes both parameters (chain and token) with 100% coverage. The description adds a concrete example endpoint with a specific token address, which could help agents understand the expected format, but it doesn't add semantic meaning beyond what the schema provides. Thus a 3 is appropriate given the high schema coverage.

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 returns the NFT contract's name, symbol, and the token standards it claims via supportsInterface, specifically listing ERC-165, ERC-721, ERC-721Metadata, and ERC-1155. This distinguishes it from sibling tools like chain_nft_balance or chain_nft_owner, which address different aspects of NFTs.

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 context: it lists supported chains and the cost per call, and gives an exact byte-identical API endpoint. It doesn't explicitly say when to prefer this over alternative tools, but the purpose (metadata and standards) is clear enough to guide selection. It doesn't mention exclusions or alternatives, so it's not a full 5.

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