> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hyphaedb.com/llms.txt
> Use this file to discover all available pages before exploring further.

# store

> Store a memory cell over MCP; the server embeds it, stamps the authenticated source agent, and gossips it.

Store a memory cell. The server computes its embedding, stamps the authenticated `source_agent`, and gossips the resulting diff to interested agents. It returns the new node id.

Dispatches to the `store` internal service method.

## Parameters

| Name              | Type   | Required | Default | Description                                                                                                                                        |
| ----------------- | ------ | -------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| `content`         | string | Yes      | —       | The cell content to store.                                                                                                                         |
| `cell_type`       | string | Yes      | —       | The cell type. One of `Decision`, `Constraint`, `Risk`, `Pattern`, `Lesson`, `Fact`, `Preference`, `Context`, `Task`. Drives energy and promotion. |
| `salience`        | number | No       | `0.5`   | Salience hint in `[0, 1]`; higher reaches further during gossip.                                                                                   |
| `scene_id`        | string | No       | —       | UUID of a scene this cell belongs to.                                                                                                              |
| `source_ref`      | object | No       | —       | Provenance back-reference: `{ "kind": string, "locator": string }` (for example `file:line` or a URL).                                             |
| `metadata`        | object | No       | `{}`    | Structured metadata.                                                                                                                               |
| `idempotency_key` | string | No       | —       | A replayed key returns the original node id instead of creating a duplicate.                                                                       |

There is no `source_agent` or `tenant_id` parameter. The server stamps identity from the authenticated principal — never from the request body. See [Trust and provenance](/concepts/trust-and-provenance).

## Returns

```json theme={null}
{ "node_id": "<uuid>" }
```

Returned as the `structuredContent` payload, mirrored in the text content block.

## Example

Request:

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "store",
    "arguments": {
      "content": "Use pgvector for the V1 storage backend.",
      "cell_type": "Decision",
      "salience": 0.9,
      "source_ref": { "kind": "file", "locator": "specs/hyphae-storage.md:42" }
    }
  }
}
```

Response:

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "content": [
      { "type": "text", "text": "{\"node_id\":\"6f9619ff-8b86-d011-b42d-00cf4fc964ff\"}" }
    ],
    "structuredContent": { "node_id": "6f9619ff-8b86-d011-b42d-00cf4fc964ff" },
    "isError": false
  }
}
```

## Annotations

The tool's MCP behaviour hints, as emitted in `tools/list` (advisory display metadata — see [the annotations contract](/mcp/overview#tool-annotations)):

| `readOnlyHint` | `destructiveHint` | `idempotentHint` | `openWorldHint` |
| -------------- | ----------------- | ---------------- | --------------- |
| `false`        | `false`           | `false`          | `false`         |

A write that mints a fresh cell per call — additive (nothing is destroyed), and not idempotent: `idempotency_key` is optional, so a repeat without one stores a second cell.

## Related

* [recall](/mcp/tools/recall) and [query](/mcp/tools/query) to find stored cells.
* [Gossip propagation](/concepts/gossip-propagation) and the [energy model](/concepts/energy-model) for how salience and cell type drive reach.