Duplicate Tool Alias

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:

{
  "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.

Overview

Connectors

Integrations

Workflow Reference

Webhook Reference

Security Reference

Architecture Reference

Error Reference

Model Inference Reference

Rosetta Stone Reference

UI Reference

SDKs

Glossary

Billing

Error message

When this error occurs

How to fix

​Error message

​When this error occurs

​How to fix

Error message

When this error occurs

How to fix