Koskamo

Shinjuku Shield MCP

A community MCP server that enables AI agents to make private x402 payments on Solana using a self-custody shielded wallet. It allows agents to shield USDC, pay any x402 endpoint without revealing the payer's identity on-chain, and interact with the Shinjuku Undermarket game. The server handles privacy work off-chain and settles payments instantly, requiring no SOL for fees as the facilitator covers network costs.

Package and access

Local package with source-attributed installation metadata. Koskamo does not execute packages during review.

Shinjuku Shield MCP logo, by Shinjuku StaitionCommunity listingLocal stdioSource reviewed; not executedPublished by Shinjuku Staition
Vendor documentation

What you can do with it

  • Shield USDC into a private balance for agent payments
  • Pay any Solana x402 endpoint privately without exposing wallet address
  • Interact with the Shinjuku Undermarket 3D game using AI agents
  • Set up self-custody wallet with no RPC keys or API sign-ups

Source and maintenance

Community listingRegistry 0.3.131
Maintenance checked

Packages and installation

Source-provided package data. Koskamo has not executed or live-probed this package.

shinjuku-shield 0.3.131

npmnpx
shinjuku-shield package definition
{
  "version": "0.3.131",
  "transport": "stdio",
  "identifier": "shinjuku-shield",
  "runtimeHint": "npx",
  "registryType": "npm",
  "registryBaseUrl": "https://registry.npmjs.org",
  "packageArguments": [
    {
      "type": "positional",
      "value": "mcp",
      "valueHint": "command",
      "description": "The wallet command that runs the MCP server on stdio."
    },
    {
      "name": "--max-payment",
      "type": "named",
      "format": "number",
      "description": "The most one payment may cost, in USDC (0.05 = 5 cents). Optional (default: no limit); setup writes the caps you set to config.json.",
      "placeholder": "0.05"
    },
    {
      "name": "--max-session",
      "type": "named",
      "format": "number",
      "description": "The most this wallet may pay in any 24 hours, from every MCP process together, in USDC (0.2 = 20 cents). Optional (default: no limit); setup writes the caps you set to config.json.",
      "placeholder": "0.2"
    },
    {
      "name": "--pool",
      "type": "named",
      "default": "CDtxyRjCUs2pu7t3U9TwtpnZwyxBFZ4dKXvb4RCmXHXv",
      "description": "The shielded pool. The wallet file is $SHIELDED_WALLET_HOME/<pool>/wallet.json."
    },
    {
      "name": "--program",
      "type": "named",
      "default": "8PYPw3FSFTMbvSneXdcoH6jNoN4VD23nHwPY2A2riUy1",
      "description": "The shielded pool program."
    },
    {
      "name": "--memo-service",
      "type": "named",
      "default": "https://pay.shinjukustaition.com",
      "description": "The facilitator that serves the encrypted memos. Its RPC relay serves reads without --rpc-file."
    },
    {
      "name": "--passphrase-file",
      "type": "named",
      "format": "filepath",
      "description": "Absolute path of a private file that holds the wallet passphrase. Without it, SHIELDED_WALLET_PASSPHRASE."
    },
    {
      "name": "--proof-tools",
      "type": "named",
      "format": "filepath",
      "description": "Absolute path of proof-tools.json. Turns wallet_shield on and is needed to pay shielded-exact."
    },
    {
      "name": "--exit-proof-tools",
      "type": "named",
      "format": "filepath",
      "description": "Absolute path of exit-proof-tools.json. With --profile and --proof-tools, turns wallet_unshield on."
    },
    {
      "name": "--profile",
      "type": "named",
      "format": "filepath",
      "description": "Absolute path of public-profile.json (the facilitator's public profile). Needed for wallet_unshield."
    },
    {
      "name": "--unshield-to",
      "type": "named",
      "isRepeated": true,
      "description": "A public Solana address that wallet_unshield sends to with no confirmation. Never the wallet's own key."
    },
    {
      "name": "--max-unshield",
      "type": "named",
      "format": "number",
      "description": "The most one wallet_unshield call may send, and the most this wallet may send in any 24 hours, in USDC (1 = 1 USDC)."
    },
    {
      "name": "--max-shield",
      "type": "named",
      "format": "number",
      "description": "The most one wallet_shield deposit may move, and the most this wallet may shield in any 24 hours, in USDC (1 = 1 USDC)."
    },
    {
      "name": "--max-per-host-day",
      "type": "named",
      "format": "number",
      "description": "The most one seller host may receive in 24 hours, in USDC."
    },
    {
      "name": "--allow-host",
      "type": "named",
      "isRepeated": true,
      "description": "Pay only this seller host (host or host:port)."
    },
    {
      "name": "--rpc-file",
      "type": "named",
      "format": "filepath",
      "description": "Absolute path of a private file with your own Solana RPC URL. Without it, reads go to the facilitator relay."
    },
    {
      "name": "--no-auto-pockets",
      "type": "named",
      "description": "Stop the idle return of pockets that an older version filled to the shielded balance. Standard exact sellers are paid through Shinjuku (float pay); no pocket is filled."
    }
  ],
  "runtimeArguments": [
    {
      "name": "--no-audit",
      "type": "named",
      "description": "npx skips npm's audit request when it installs a new version (that request once held the start for 5 minutes)."
    },
    {
      "name": "--no-fund",
      "type": "named",
      "description": "npx skips npm's funding message when it installs a new version."
    }
  ],
  "environmentVariables": [
    {
      "name": "SHIELDED_WALLET_HOME",
      "format": "filepath",
      "description": "The private folder that holds the encrypted wallet and config.json. Default: ~/.carbon-shielded-wallet (the folder that setup uses)."
    },
    {
      "name": "SHIELDED_WALLET_PASSPHRASE",
      "description": "The wallet passphrase, if you do not use --passphrase-file."
    }
  ]
}

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Connect from your client

Each snippet configures the same source-provided package; replace placeholders before use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Cursor

Merge this local stdio configuration, replace every placeholder environment value, and restart Cursor. Koskamo has not executed this package.
Cursor configuration
{
  "mcpServers": {
    "shinjuku-shield-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "shinjuku-shield@0.3.131",
        "mcp"
      ],
      "env": {
        "SHIELDED_WALLET_HOME": "<YOUR_SHIELDED_WALLET_HOME>",
        "SHIELDED_WALLET_PASSPHRASE": "<YOUR_SHIELDED_WALLET_PASSPHRASE>"
      }
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.
Cline configuration
{
  "mcpServers": {
    "shinjuku-shield-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "shinjuku-shield@0.3.131",
        "mcp"
      ],
      "env": {
        "SHIELDED_WALLET_HOME": "<YOUR_SHIELDED_WALLET_HOME>",
        "SHIELDED_WALLET_PASSPHRASE": "<YOUR_SHIELDED_WALLET_PASSPHRASE>"
      }
    }
  }
}

VS Code

Merge this local stdio configuration, replace every placeholder environment value, and restart VS Code. Koskamo has not executed this package.
VS Code configuration
{
  "servers": {
    "shinjuku-shield-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "shinjuku-shield@0.3.131",
        "mcp"
      ],
      "env": {
        "SHIELDED_WALLET_HOME": "<YOUR_SHIELDED_WALLET_HOME>",
        "SHIELDED_WALLET_PASSPHRASE": "<YOUR_SHIELDED_WALLET_PASSPHRASE>"
      }
    }
  }
}

Claude Desktop

Merge this local stdio configuration, replace every placeholder environment value, and restart Claude Desktop. Koskamo has not executed this package.
Claude Desktop configuration
{
  "mcpServers": {
    "shinjuku-shield-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "shinjuku-shield@0.3.131",
        "mcp"
      ],
      "env": {
        "SHIELDED_WALLET_HOME": "<YOUR_SHIELDED_WALLET_HOME>",
        "SHIELDED_WALLET_PASSPHRASE": "<YOUR_SHIELDED_WALLET_PASSPHRASE>"
      }
    }
  }
}

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