# previous_trading_day

Get the previous trading day before the given date.

Agent View of the PolicyLayer registry record for `previous_trading_day`. HTML page: https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/previous-trading-day

## Facts

- Tool: `previous_trading_day`
- Server: A-Share MCP Server (`24mlight/a-share-mcp-is-just-i-need`) — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need.md
- Homepage: https://github.com/24mlight/a-share-mcp-is-just-i-need
- Risk category: Read (Low risk)
- Registry record: grade A, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "previous_trading_day",
    "arguments": {}
  }
}
```

## Why previous_trading_day is rated Low

This tool fetches calendar/market data (the date of the previous trading day) based on an input parameter. It has no side effects, performs no state changes, and involves no financial transactions or code execution. It is a simple informational lookup, consistent with the Read category.

From the tool's own definition: "Tool name 'previous_trading_day' and description 'Get the previous trading day before the given date' indicate a query operation that retrieves date information without modifying, executing code, deleting, or moving money."

## Use case

AI agents call previous_trading_day to retrieve information from A-Share MCP Server without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches A-Share MCP Server:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "previous_trading_day": {}
  }
}
```

## Other tools on A-Share MCP Server (40)

- `get_adjust_factor_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-adjust-factor-data.md
- `get_all_stock` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-all-stock.md
- `get_balance_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-balance-data.md
- `get_cash_flow_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-cash-flow-data.md
- `get_deposit_rate_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-deposit-rate-data.md
- `get_dividend_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-dividend-data.md
- `get_dupont_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-dupont-data.md
- `get_fina_indicator` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-fina-indicator.md
- `get_forecast_report` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-forecast-report.md
- `get_growth_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-growth-data.md
- `get_historical_k_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-historical-k-data.md
- `get_hs300_stocks` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-hs300-stocks.md
- `get_index_constituents` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-index-constituents.md
- `get_industry_members` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-industry-members.md
- `get_last_n_trading_days` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-last-n-trading-days.md
- `get_latest_trading_date` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-latest-trading-date.md
- `get_loan_rate_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-loan-rate-data.md
- `get_market_analysis_timeframe` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-market-analysis-timeframe.md
- `get_money_supply_data_month` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-money-supply-data-month.md
- `get_money_supply_data_year` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-money-supply-data-year.md
- `get_month_end_trading_dates` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-month-end-trading-dates.md
- `get_operation_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-operation-data.md
- `get_performance_express_report` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-performance-express-report.md
- `get_profit_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-profit-data.md
- `get_recent_trading_range` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-recent-trading-range.md
- `get_required_reserve_ratio_data` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-required-reserve-ratio-data.md
- `get_stock_analysis` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-stock-analysis.md
- `get_stock_basic_info` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-stock-basic-info.md
- `get_stock_industry` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-stock-industry.md
- `get_suspensions` — Read — https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need/get-suspensions.md
- …and 10 more: https://policylayer.com/tools/24mlight-a-share-mcp-is-just-i-need.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=24mlight-a-share-mcp-is-just-i-need · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/24mlight-a-share-mcp-is-just-i-need