# MCP Tool-Call Stream

`POST https://api.astroway.info/v1/mcp/tool-call-stream`

SSE-stream of a tool call envelope.

Group: MCP Advanced. Auth: `X-Api-Key` header. Operation ID: `mcp_tool-call-stream`.

## Parameters

| Name | In | Required | Type | Description |
|---|---|---|---|---|
| `fields` | query | no | string | Comma-separated dotted paths, relative to `data`, to keep in the response. A path is applied to every element of an array, so `planets.name` means the name of each planet. Paths that match nothing come back in `_fields_unmatched`; a list where nothing matches at all is a 400, because an empty object would be a confident wrong answer. |
| `precision` | query | no | integer | Round every non-integer number in the response to this many decimal places. Integers are left alone, because an id is not a measurement. Ecliptic longitudes ship with fourteen decimals by default; 2 is about a tenth of an arcminute. |

## Request body

| Field | Type | Required | Description |
|---|---|---|---|
| `tool` | string | yes |  |
| `args` | object | no |  |
| `language` | "uk" \| "en" \| "ru" \| "es" \| "pl" \| "de" \| "fr" \| "it" \| … | no |  |

```json
{
  "tool": "chart",
  "args": {
    "date": "1990-05-15",
    "time": "15:30:00",
    "timezone": "Europe/Kyiv",
    "latitude": 50.45,
    "longitude": 30.52
  }
}
```

## Responses

| Status | Meaning |
|---|---|
| 200 | Server-sent events. Each frame is `data: ` followed by a JSON object: `{"type":"tool-start","tool","args"}`, then `{"type":"progress","stage","text"}` per stage, then `{"type":"done","tool","language","note"}`. |
| 400 | Validation error |
| 401 | Missing or invalid API key |

## Example

```bash
curl -X POST https://api.astroway.info/v1/mcp/tool-call-stream \
  -H "X-Api-Key: aw_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "tool": "chart", "args": { "date": "1990-05-15", "time": "15:30:00", "timezone": "Europe/Kyiv", "latitude": 50.45, "longitude": 30.52 } }'
```

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