# tengu_v3_reference_history

IDENTIFIER HISTORY for one symbol — every identifier this security has ever been bound to, with the dates each binding started and ended, plus the dated events where the ISSUER changed its name, ticker or CUSIP. This is the part of a crosswalk a current-state table cannot give you: it answers 'what was this on 2015-06-30', 'when did this CUSIP change' and 'what was this company called then'. Returns the timeline grouped by identifier rung (each entry with valid_from, valid_thru and whether it is still current), the issuer change events with what changed at each one, and — with as_of — the exact set of identifiers in force on that date. Use it to back-map a historical holdings file, to audit identifier drift in your own data, or to explain a ticker that no longer exists. STALENESS, stated rather than implied: the issuer change log is a VINTAGE snapshot that lags the live security master (as-of 2026-04-20 when this shipped, 104 days old, newest change event 2026-01-30). Its age in days and its expected cadence are in every response, and any disagreement between it and the live spine is named explicitly rather than blended into one confident answer. Coverage is a number: 969,333 identifier bindings on file, 759,618 of them retired, 38,850 of 77,313 securities carrying at least one prior ticker.

Agent View of the PolicyLayer registry record for `tengu_v3_reference_history`. HTML page: https://policylayer.com/tools/tengu-mcp/tengu-v3-reference-history

## Facts

- Tool: `tengu_v3_reference_history`
- Server: Tengu (`Hlobo-dev/tengu-mcp`) — https://policylayer.com/tools/tengu-mcp.md
- Homepage: https://github.com/Hlobo-dev/tengu-mcp
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 4 (1 required)
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `as_of` | string | no |  |
| `symbol` | string | yes | Path parameter 'symbol' (required). |
| `prefer_country` | string | no |  |
| `include_change_log` | boolean | no |  |

Parameters from the server's own tool schema.

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

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "tengu_v3_reference_history",
    "arguments": {
      "symbol": "<symbol>"
    }
  }
}
```

## Why tengu_v3_reference_history is rated Medium

An AI agent can call tengu_v3_reference_history faster than any human can review: one bad instruction and it creates or modifies resources in Tengu by the hundred, each call as confident as the last.

## Use case

AI agents use tengu_v3_reference_history to create or update resources in Tengu, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Tengu environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Tengu:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "tengu_v3_reference_history": {
      "limits": [
        {
          "counter": "tengu_v3_reference_history_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Tengu (336)

- `tengu_v3_features_dataset` — Destructive — https://policylayer.com/tools/tengu-mcp/tengu-v3-features-dataset.md
- `tengu_v3_intel_borrow_cost_history` — Destructive — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-borrow-cost-history.md
- `tengu_v3_intel_insider_flow` — Destructive — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-insider-flow.md
- `tengu_v3_intel_risk_free_rate` — Destructive — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-risk-free-rate.md
- `tengu_v3_intel_sec13f_changes` — Destructive — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-sec13f-changes.md
- `tengu_v3_backtest_run_detail` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-backtest-run-detail.md
- `tengu_v3_briefing_daily` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-briefing-daily.md
- `tengu_v3_factor_predictors` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-factor-predictors.md
- `tengu_v3_intel_darkpool_history` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-darkpool-history.md
- `tengu_v3_intel_gex_history` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-gex-history.md
- `tengu_v3_intel_ml_drivers` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-ml-drivers.md
- `tengu_v3_intel_ml_prediction` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-ml-prediction.md
- `tengu_v3_intel_options_flow_history` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-intel-options-flow-history.md
- `tengu_v3_news_sentiment_history` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-news-sentiment-history.md
- `tengu_v3_optimizer_latest` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-optimizer-latest.md
- `tengu_v3_prices_corporate_actions` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-prices-corporate-actions.md
- `tengu_v3_private_markets_service_provider_relations` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-private-markets-service-provider-relations.md
- `tengu_v3_reference_coverage` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-reference-coverage.md
- `tengu_v3_supply_chain_relationships` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-supply-chain-relationships.md
- `tengu_v3_tape_bars` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-tape-bars.md
- `tengu_v3_validation_trials` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-validation-trials.md
- `tengu_v3_workforce_layoffs` — Execute — https://policylayer.com/tools/tengu-mcp/tengu-v3-workforce-layoffs.md
- `tengu_cache_stats` — Read — https://policylayer.com/tools/tengu-mcp/tengu-cache-stats.md
- `tengu_copilot_decision_review` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-decision-review.md
- `tengu_copilot_live_ic_drift` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-live-ic-drift.md
- `tengu_copilot_macro_regime` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-macro-regime.md
- `tengu_copilot_score_ticker` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-score-ticker.md
- `tengu_copilot_signal_health` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-signal-health.md
- `tengu_copilot_ticker_full` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-ticker-full.md
- `tengu_copilot_ticker_smartmoney` — Read — https://policylayer.com/tools/tengu-mcp/tengu-copilot-ticker-smartmoney.md
- …and 306 more: https://policylayer.com/tools/tengu-mcp.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=tengu-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/tengu-mcp