# similarity

`station__edit-distance__similarity` · external (needs EXECUTION_BACKEND_URL configured) · domain `edit-distance` · pv-relevance `non-pv`

Check if two strings meet a similarity threshold. Returns similarity score and pass/fail against threshold. Useful for drug name matching gates.

> **Note:** This tool routes through an external execution backend. If `EXECUTION_BACKEND_URL` is unset on the server, calls return JSON-RPC error `-32603 "Tool execution backend not configured"`. Tools with `backend: native` execute in-process and are always callable.

## Agent metadata

- `idempotent`: unknown
- `read_only`: unknown
- `expected_latency_ms`: unknown (not yet contract-tested)
- `cost_tokens_estimate`: unknown

## Input schema

- `source` *string* (required) — Source string
- `target` *string* (required) — Target string
- `threshold` *number* — Minimum similarity to pass (default 0.8)

## Example call

```json
POST /api/mcp
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "station__edit-distance__similarity",
    "arguments": {
      "source": "",
      "target": ""
    }
  }
}
```

## Related

- [/tools](/tools) — all 3062 tools
- [/tools/edit-distance__similarity](/tools/edit-distance__similarity) — HTML page
- [/tools/edit-distance__similarity/json](/tools/edit-distance__similarity/json) — JSON form (agent-friendly)
- [/api/mcp](/api/mcp) — endpoint
- [/AGENTS.md](/AGENTS.md) — agent guide