# `TMCP021` list_references_to returns empty list for unreferenced requirement

Query which requirements reference a requirement that no other requirement points to, verify an empty list is returned

:::{dropdown} Is a test for
:open: 
:icon: check-circle-fill
:color: primary

[`MCP007` List requirements referencing another](/requirements/MCP007)
:::
:::{dropdown} Automated in
:open: 
:icon: check-circle-fill
:color: success

{fab}`python` [`test_list_references_to_empty`](https://github.com/agagniere/speky/blob/master/tests/test_mcp_server.py#L574)
:::
:::{dropdown} Source
:icon: file-code
:color: info

__Source file__: [`specs/mcp/test_07.yaml`](https://github.com/agagniere/speky/blob/master/specs/mcp/test_07.yaml)

__Loaded from__: [`speky_mcp`](https://github.com/agagniere/speky/blob/master/specs/mcp/mcp.toml)

:::

## Initial state
The expected state is the final state of
[`TMCP003` Initialize the MCP server](/tests/TMCP003)
## Procedure
### Step 1
The client calls `list_references_to` with ID `RF01`, which no requirement references
```json
{
  "id": 2,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "list_references_to",
    "arguments": {"id": "RF01"}
  }
}

```
### Step 2
Verify an empty list is returned
```json
{
  "id": 2,
  "jsonrpc": "2.0",
  "result": {
    "structuredContent": {
      "requirements": []
    }
  }
}

```