Crypto, web, finance and app data tools

NFT Owner

nft_owner

Current owner of an ERC-721 NFT by contract and token ID. Use to verify ownership for token gating, sales or airdrops.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "contract": "<contract>",
      "token_id": "<token_id>"
    },
    "name": "nft_owner"
  }
}

Input Schema

Name	Required	Default
`chain`	No	ethereum
`contract`	Yes
`token_id`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 23, 2026

TDQS

B3.3/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden. 'Current owner' implies a read, but there is no disclosure of what happens for nonexistent or burned tokens, whether zero-address is returned, or which chains are supported — meaningful gaps for a multi-chain ownership lookup.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tightly written sentences with the identity of the tool front-loaded and use cases second. No waste or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The presence of an output schema removes the need to describe return values, which the description correctly skips. However, for a 3-parameter, multi-chain ownership lookup with zero annotations, the undocumented chain parameter and unaddressed edge cases leave it only minimally complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It mentions contract and token ID only conceptually, and completely omits the 'chain' parameter (default 'ethereum'), leaving an agent unaware it can query networks other than Ethereum.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Current owner of an ERC-721 NFT by contract and token ID.' The ERC-721 framing implicitly separates it from erc20_balance (fungible) and nft_metadata (metadata, not ownership), but neither sibling is named explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete intended use cases ('token gating, sales or airdrops'), which tells an agent the context in which to reach for this tool. It stops short of exclusions or pointing to alternatives such as nft_metadata when metadata rather than ownership is the goal.

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

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