x402 agent toolkit: service finder, payment safety, Solana & web tools

by dev.workers.moneytools.x402-pay-precheck

NFT metadata + owner

nft_metadata

Read-onlyIdempotent

ERC-721/1155 token: standard, collection name, owner, tokenURI resolved (IPFS/Arweave/data URI) and the metadata JSON with image URL; says whether metadata is on-chain, IPFS or a mutable server. Free: 10 calls/day; then $0.002/call via x402 (MCP params._meta["x402/payment"] or HTTP) or X-API-Key credits. [served by tools.moneytools.dev]

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": {
      "chain": "<chain>",
      "contract": "<contract>",
      "tokenId": "<tokenId>"
    },
    "name": "nft_metadata"
  }
}

Input Schema

Name	Required	Description
`chain`	Yes	chain: base, ethereum, arbitrum, optimism, polygon, bsc, avalanche
`tokenId`	Yes	token id
`contract`	Yes	NFT contract

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 4, 2026

TDQS

A3.6/5.0

Behavior4/5

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

Annotations already cover read-only, idempotent, non-destructive, open-world behavior, and the description still adds real substance: it resolves IPFS/Arweave/data URIs and reports whether metadata is on-chain, IPFS-hosted, or on a mutable server. It also discloses the cost model (10 free calls/day, $0.002/call) and the payment mechanisms (x402 via params._meta or HTTP, or X-API-Key credits), which is meaningful context beyond the annotations. It stops short of describing failure behavior for unresolvable or non-standard tokens.

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

Conciseness4/5

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

The payload description is front-loaded in the first clause, followed by resolution and hosting detail, then billing. It is dense but each clause carries information; the payment sentence is long but earns its place by stating concrete price and channel options.

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

Completeness5/5

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

An output schema exists, so return values need not be spelled out, yet the description still summarizes the key fields and adds hosting-provenance and pricing information an agent needs before calling. For a three-parameter read tool with full schema coverage, nothing essential is missing.

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

Parameters3/5

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

Schema description coverage is 100% and all three parameters are documented in the schema, including the supported chain list. The description adds no format or constraint detail beyond that, so the baseline of 3 applies.

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?

The description names a specific resource (ERC-721/1155 token metadata) and enumerates exactly what comes back: standard, collection name, owner, resolved tokenURI, and the metadata JSON with image URL. It is not a tautology of the title, but it never distinguishes itself from plausible siblings that also resolve URIs or owners, so an agent cannot fully separate it by description alone.

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

Usage Guidelines2/5

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

There is no when-to-use guidance and no named alternative; the agent must infer from the input keys (chain/contract/tokenId) that this is the NFT-specific lookup. The only operational guidance is commercial (free tier then paid), which does not help select between this and tools like ip_owner or url_metadata.

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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