shadcn-ui/ui · error

No tool arguments provided.

Error message

No tool arguments provided.

What it means

The MCP CallTool handler requires request.params.arguments to be present — even an empty object for no-arg tools. Some clients send null/undefined for tools taking no arguments; this guard rejects that before dispatching into the tool switch.

Source

Thrown at packages/shadcn/src/mcp/index.ts:176

                "Array of items to get the add command for prefixed with the registry name (e.g., ['@shadcn/button', '@shadcn/card'])"
              ),
          })
        ),
      },
      {
        name: "get_audit_checklist",
        description:
          "After creating new components or generating new code files, use this tool for a quick checklist to verify that everything is working as expected. Make sure to run the tool after all required steps have been completed.",
        inputSchema: zodToJsonSchema(z.object({})),
      },
    ],
  }
})

server.setRequestHandler(CallToolRequestSchema, async (request) => {
  try {
    if (!request.params.arguments) {
      throw new Error("No tool arguments provided.")
    }

    switch (request.params.name) {
      case "get_project_registries": {
        const config = await getMcpConfig(process.cwd())

        if (!config?.registries) {
          return {
            content: [
              {
                type: "text",
                text: dedent`No components.json found or no registries configured.

                To fix this:
                1. Use the \`init\` command to create a components.json file
                2. Or manually create components.json with a registries section`,
              },
            ],

View on GitHub (pinned to efac598707)

Solutions

1. Update the MCP client to always send arguments ({} for no-arg tools).
2. If you control the client, ensure params.arguments is an object before sending the request.

Example fix

// before (client call)
client.callTool({ name: 'get_audit_checklist', arguments: null })
// after
client.callTool({ name: 'get_audit_checklist', arguments: {} })

// On the client side: always pass an arguments object, even for no-arg tools.
await client.callTool({
  name: "get_audit_checklist",
  arguments: {},
})

type CallToolRequest = { params: { name: string; arguments?: Record<string, unknown> | null } }

function hasMcpArgs(req: CallToolRequest): req is { params: { name: string; arguments: Record<string, unknown> } } {
  return req?.params?.arguments != null && typeof req.params.arguments === "object"
}

When it happens

Trigger: An MCP client (Claude Code, Cursor, VS Code, Codex, OpenCode) calls a shadcn MCP tool but omits the arguments field or sends null — common for get_audit_checklist whose schema is z.object({}).

Common situations: Client bug, older client spec version, a client that treats 'no parameters' as 'no arguments key' rather than arguments:{}.

Related errors

• Tool ${request.params.name} not found
• Unknown client: ${client}. Available clients: ${CLIENTS.map(
• Base color "${baseColorName}" or theme "${themeName}" not fo
• Unknown item: "${designSystemConfig.item}".
• Font "${designSystemConfig.font}" not found

AI-assisted analysis of shadcn-ui/ui@efac598707 (2026-08-12). Data as JSON: /api/errors/c4bb846898c8cb90. Report an issue: GitHub.