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

Adds substantial context beyond annotations: error behavior (404 missing contract, 422 nonexistent token, both uncharged), pricing model ($0.01/call, first 25 free, failed calls free), and clarifies that the tool is read-only and changes nothing. It also explains why idempotentHint=false by noting each successful repeat incurs a charge.

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-loads the definition in the first sentence, then layers usage, alternatives, error codes, a concrete example, and pricing without any filler. Every sentence contributes actionable information for correct invocation.

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?

No output schema exists, but the description states what is returned (owner, name, symbol) and covers error codes, pricing, and safety profile. An agent has everything needed to call the tool correctly and understand the outcome.

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%, so both parameters are fully documented in the input schema. The description adds an inline example with plausible values for contract and tokenId, but does not add syntax or format details beyond what the schema already says.

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 (owner of an NFT), the exact resource (ERC-721 token id on Base), and the returned data (owner, name, symbol). It explicitly distinguishes itself from base_nft_balance and base_nft_metadata, so an agent can select it without opening the schema.

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?

Provides concrete scenarios (verify holder before trade, mint gate, airdrop) and names the alternative siblings for balance and metadata queries. The when-to-use and when-to-use-something-else rules are fully explicit.

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