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

Goes well beyond the readOnlyHint/openWorldHint annotations: it discloses the billing model, the exact cases that are not charged (invalid input, nonexistent token, Base unreachable), which metadata protocols are resolved (ipfs://, ar://, https, inline on-chain), and the 100 KB cap on inline images. Those are the operational traits an agent needs before spending money on a call.

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?

Front-loaded with the core action and return fields in the first sentence, then short sentences for the optional param, mutability, and billing. Dense and mostly waste-free, though "Read-only" restates the annotation and the field list is slightly packed.

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 carries the burden of describing return values and does so explicitly (owner type, collection name/symbol, name, description, image, animation, traits). Combined with the cost and failure-mode notes, an agent has everything needed to call it correctly.

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 description coverage is 100%, so the baseline is 3. The description does add real meaning for owner (confirms a wallet holds the token, including ERC-1155 balance) and alludes to includeImage via inline on-chain metadata, but tokenId format and contract address semantics are left entirely to the schema.

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?

States a specific verb and resource with scope: look up one NFT on Base by contract and token ID, and enumerates exactly what comes back (owner, collection name/symbol, metadata fields). The ERC-721/ERC-1155 qualifier and per-token granularity clearly separate it from fungible-token siblings like chain_token and from collection-wide tools like token_holders.

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?

"Pass owner to confirm a wallet holds it" gives a concrete condition for the optional parameter, and "Paid via x402; see list_prices" routes the agent to the right pricing sibling. It does not, however, name any alternative or exclusion (e.g. when to prefer chain_contract or token_holders), so usage is clear but not fully disambiguated.

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