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

# Duplicate Tool Alias

> The same alias is used twice in mcp_servers.

**HTTP status:** 400

## Error message

```
duplicate mcp_server aliases (must be unique): {dupes}
```

## When this error occurs

Aliases namespace each MCP server's tools — when the model emits a call like
`{alias}-{tool_name}`, the workflow routes by `alias`. Two MCP servers with the same alias
would make routing ambiguous, so the API rejects them up front.

Caller-declared tools (in top-level `tools[]`) have **no** alias — the dash in the wire
name is the routing discriminator. Uniqueness only matters within `mcp_servers[]`.

## How to fix

Pick distinct aliases for each MCP server:

```json theme={null}
{
  "mcp_servers": [
    { "alias": "docs", ... },
    { "alias": "wiki", ... }
  ]
}
```

If you genuinely need two MCP servers for related capabilities, distinguish them
semantically (`docsv1`, `docsv2`) rather than reusing one alias.