mercury_list_credit_accounts

Instructions

Implementation Reference

• src/tools/credit.ts:38-41 (handler)

  The handler function that executes the tool logic: calls client.get('/credit') and returns the result as text.

  async () => {
    const data = await client.get("/credit");
    return textResult(data);
  },

• src/tools/credit.ts:37-37 (schema)

  Input schema: empty object ({}) since the tool takes no arguments.

  {},

• src/tools/credit.ts:24-43 (registration)

  The tool is registered via defineTool() inside registerCreditTools(), with name 'mercury_list_credit_accounts', description, empty schema, handler, and annotations (readOnlyHint: true, openWorldHint: true).

  export function registerCreditTools(server: McpServer, client: MercuryClient): void {
    defineTool(
      server,
      "mercury_list_credit_accounts",
      [
        "List Mercury IO Credit card accounts (charge cards, distinct from deposit accounts).",
        "",
        "USE WHEN: enumerating IO Credit accounts to find their balance, statement closing date, or to feed an ID into `mercury_list_credit_transactions`. Wraps `GET /credit` (documented under Credit › List all credit accounts in the Mercury API reference).",
        "",
        "DO NOT USE: for deposit accounts (checking/savings/treasury) — use `mercury_list_accounts`, which hits a different endpoint (`/accounts`).",
        "",
        "RETURNS: `{ accounts: [{ id, status, availableBalance, currentBalance, ... }] }`.",
      ].join("\n"),
      {},
      async () => {
        const data = await client.get("/credit");
        return textResult(data);
      },
      { title: "List Credit Accounts", readOnlyHint: true, openWorldHint: true },
    );

• src/tools/index.ts:20-24 (registration)

  registerAllTools() calls registerCreditTools() to register all credit-related tools including mercury_list_credit_accounts.

  export function registerAllTools(server: McpServer, client: MercuryClient): void {
    // Banking
    registerAccountTools(server, client);
    registerCardTools(server, client);
    registerCreditTools(server, client);

• src/tools/_shared.ts:28-54 (helper)

  The defineTool helper wraps the handler and registers the tool on the MCP server via server.registerTool.

  export function defineTool<S extends ZodRawShape>(
    server: McpServer,
    name: string,
    description: string,
    inputSchema: S,
    handler: (args: z.infer<z.ZodObject<S>>) => Promise<ToolResult>,
    annotations: ToolAnnotations,
  ): void {
    const wrapped = wrapToolHandler(name, handler);
    const strictSchema = z.object(inputSchema).strict();
    // MCP behavioral annotations (readOnlyHint / destructiveHint /
    // idempotentHint / openWorldHint) — declared machine-readable so
    // hosts and rubrics (TDQS / Glama Behavior dimension) can detect
    // tool semantics without scraping the prose description. Required
    // (not optional) so every new tool ships with explicit semantics —
    // forgetting the annotation now fails typecheck instead of
    // silently shipping a tool with no hint set.
    // The MCP SDK overloads `registerTool` with shape narrowing the runtime
    // strict-schema and the wrapped callback can't satisfy through generics.
    // Both casts are runtime-safe — the signatures only diverge at the type
    // level. Asserted by the existing tool-registration tests.
    (server.registerTool as unknown as (...a: unknown[]) => unknown)(
      name,
      { description, inputSchema: strictSchema, annotations },
      wrapped,
    );
  }