# US Treasury Constant-Maturity Yield History

> US Treasury Constant-Maturity Yield History is a paid API for AI agents from agent402.tools, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Returns the last N business days of US Treasury constant-maturity yields (oldest to newest) sourced from FRED DGS series.

## Facts

- Endpoint: GET https://agent402.tools/api/treasury-yield-history
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-constant-maturity-yield-history-bd2278ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ow1m6MWQGPaGrivXW4jca

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-treasury-constant-maturity-yield-history-bd2278ae
```

Example prompt: Can you pull the last 60 business days of US Treasury constant-maturity yields from FRED so I can see the recent trend in rates?

## When to prefer this

Use this endpoint when you need historical US Treasury constant-maturity yield data from an authoritative public-domain source (FRED/St. Louis Fed) without needing to set up your own FRED API key. Ideal for financial analysis, risk-free rate lookups, yield curve analysis, or macroeconomic modeling requiring recent Treasury rate history.

## Known failure modes

- days parameter outside 1-250 range returns validation error
- FRED upstream data unavailable causes service error
- Payment failure (402) if USDC payment not provided
- Non-business days skipped automatically — fewer rows than calendar days expected

## How this service works

Last N business days of US Treasury constant-maturity yields, oldest→newest. Source: FRED DGS* series (St. Louis Fed), public domain. ?days=30 (1-250, default 30).

## Output

A time series of US Treasury constant-maturity yield values for the requested number of business days, ordered from oldest to newest, sourced from the FRED DGS series published by the St. Louis Federal Reserve. Includes dates and yield percentages.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "days": {
       "type": "number",
       "description": "Number of business days, 1-250 (default 30)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "days",
      "count",
      "history"
     ],
     "properties": {
      "days": {
       "type": "integer"
      },
      "count": {
       "type": "integer"
      },
      "history": {
       "type": "array",
       "items": {
        "type": "object",
        "properties": {
         "yr2": {
          "type": "number"
         },
         "yr10": {
          "type": "number"
         },
         "recordDate": {
          "type": "string"
         }
        }
       }
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "days": 30,
  "count": 30,
  "history": [
   {
    "yr2": 4.71,
    "yr10": 4.46,
    "recordDate": "2026-05-01"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-constant-maturity-yield-history-bd2278ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)