LocalAI/docs/content/features/model-aliases.md

+++ disableToc = false title = "Model Aliases" weight = 14 url = "/features/model-aliases/" +++

A model alias is a model name that redirects all traffic to another configured model. Declare gpt-4 as an alias of my-llama-3 and every client calling gpt-4 is served by my-llama-3 with no client reconfiguration: the clients keep their existing model name while you control what answers them on the server side.

Declaring an alias

Create a minimal config file in your models directory:

name: gpt-4
alias: my-llama-3

That is the whole config: a name (the alias clients call) and an alias key (the target that actually serves the request). An alias may add an optional profile block.

Rules and behavior

• The target (my-llama-3) must be an existing, non-alias, enabled model. You cannot point an alias at a missing model, a disabled model, or another alias (no chains).
• Aliases are 1:1. One alias maps to exactly one target.
• The target can be swapped live by editing the config file, calling the API, using the UI, or asking the assistant. No restart is required.
• Both gpt-4 and my-llama-3 appear in GET /v1/models.
• Responses echo the requested alias: a call to gpt-4 returns gpt-4 in the response model field, not the target name.
• Usage accounting records both sides: requested gpt-4, served my-llama-3.
• Aliases work for every modality (chat, embeddings, audio, images, and so on).

To serve a name from several models with automatic fallback, use a [failover chain]({{%relref "features/model-failover" %}}).

Profile aliases

An alias can also act as a profile of its target: a different assistant on the same loaded model. Add an optional profile block; its fields are applied on top of the target's config for requests to the alias:

Field	Effect
profile.system_prompt	Replaces the target's system prompt. A system message sent by the client still takes precedence, as for any model.
profile.mcp (remote, stdio)	Replaces the target's MCP servers.
profile.mcp.auto	Enables the MCP servers on /v1/chat/completions without metadata.mcp_servers, when MCP is enabled and the caller has the mcp permission. See [MCP]({{%relref "features/mcp" %}}).
profile.client_tools: drop	Discards tools and tool_choice sent by the client.
profile.evidence_check.numbers	Marks answers that contain numbers without evidence in the request. See Evidence check.
profile.evidence_check.note	Text appended by the evidence check. Defaults to an English note.
profile.evidence_check.sources	Appends the URLs the request's MCP tools returned to an answer that names no URL. See Source line.
profile.evidence_check.sources_label	Label of the source line. Defaults to Sources.
profile.require_tool	Makes the first model call of a request call one of the profile's MCP tools. See Requiring a tool call.

name: researcher
alias: my-llama-3
profile:
  system_prompt: You are a careful research assistant. Cite your sources.
  client_tools: drop
  mcp:
    auto: true
    remote: |
      {"mcpServers": {"search": {"url": "http://search.internal/mcp"}}}

Requests to researcher run on the same backend process as my-llama-3: the model is not loaded a second time, however many profiles point at it. A separate model config with its own backend and model file would load the weights again. Fields the profile does not set are taken from the target.

The block is opt-in. Only fields inside profile are applied: top-level fields on an alias (system_prompt, mcp, sampling parameters, templates, ...) are still ignored, so an alias without a profile block behaves exactly as before. A profile block on a model that is not an alias is rejected.

MCP sessions of a profile with its own servers are kept apart from the target's, so profiles with different tool sets do not interfere with each other. GET /v1/mcp/servers/<alias> (and the prompts and resources endpoints) report the servers a chat request for the alias would use, so a profile's tool set can be checked without calling the model.

Evidence check

A profile with server-side MCP tools returns only the final answer to the client; the tool calls and their results stay on the server. When the client sends the conversation back on the next turn, that tool trail is missing, and a model may answer a follow-up question with a number it never looked up instead of calling the tool again. The evidence check marks such answers at the output, independently of the prompt:

name: bookkeeper
alias: my-llama-3
profile:
  mcp:
    auto: true
    remote: |
      {"mcpServers": {"ledger": {"url": "http://ledger.internal/mcp"}}}
  evidence_check:
    numbers: true
    # optional, defaults to the note below
    note: "_Note: this answer contains numbers that no tool returned in this turn — not verified._"

The rule is deterministic and applies to each request on its own:

1. If an MCP tool call succeeded on the server during this request, the answer is left unchanged. A call that failed (the tool could not be called or returned an error to LocalAI) delivers no evidence and does not count.
2. Otherwise every number in the final answer (a digit sequence, optionally with one . or , decimal part) is looked up among the numbers of the request as received: the profile's system prompt and the content of every system, user, assistant and tool message. 3,5 and 3.5 count as the same number.
3. If at least one number of the answer is not found, the note is appended after a blank line. In a streamed response it arrives as one additional content chunk before the final chunk.

Answers that hand tool calls to the client are not checked. The check is off unless numbers: true is set, and note without numbers: true is rejected. It flags, it does not prove: a number the client happened to mention is accepted even if the answer uses it wrongly.

Source line

A research profile usually asks the model in its system prompt to cite its sources. A model can still answer from a search result without naming a single link, and the client never sees the tool results that held them. With sources: true LocalAI adds the links at the output:

name: researcher
alias: my-llama-3
profile:
  mcp:
    auto: true
    remote: |
      {"mcpServers": {"search": {"url": "http://search.internal/mcp"}}}
  evidence_check:
    sources: true
    # optional, defaults to "Sources"
    sources_label: Quellen

Like the number check it acts on /v1/chat/completions. The rule is deterministic and applies to each request on its own:

1. Only the results of MCP tool calls that succeeded on the server during this request are read. The client's messages and failed calls are not a source.
2. If the final answer already contains an http:// or https:// URL, it is left unchanged.
3. Otherwise the distinct URLs of those tool results are collected in the order they first appear, at most five, and appended after a blank line as one line: Quellen: https://a.example/test, https://b.example/oil. Punctuation that ends a sentence is not taken as part of a URL. Parentheses inside URL paths and query parameters in JSON-encoded MCP text results are preserved.
4. If no tool result contains a URL, nothing is appended. No URL is ever made up: every link on the line was returned by a tool.

In a streamed response the line arrives as one additional content chunk before the final chunk, like the number note. Both checks can be enabled together; the number note follows the source line. sources_label without sources: true is rejected.

Requiring a tool call

A system prompt that says "always search first" does not stop a model from answering a question from its own knowledge, for example when the question comes with a picture. require_tool: true enforces the first step in the request instead:

name: researcher
alias: my-llama-3
profile:
  require_tool: true
  mcp:
    auto: true
    remote: |
      {"mcpServers": {"search": {"url": "http://search.internal/mcp"}}}

When the switch is set and a /v1/chat/completions request offers the profile's server-side MCP tools, the first model call of the request is made with tool_choice: "required". Every follow-up call of the server-side tool loop is made with the tool_choice the client sent (or none), so after the tool results the model is free to answer. A required that stayed in place would make the model call a tool again after every result and never answer until the loop's iteration limit.

How required is enforced depends on the model:

• With template.use_tokenizer_template (llama.cpp with the model's own chat template), LocalAI passes tool_choice: "required" to the backend, which constrains the output to a tool call with a grammar built from the chat template's tool-call format.
• When LocalAI builds the tool-call grammar itself, the first call's grammar leaves out the no-action function (answer) the model would otherwise reply with directly.

The first call is not forced when:

• no server-side MCP tool was offered (MCP disabled, the caller lacks the mcp permission, or the profile has no servers),
• the client set tool_choice (other than auto) or function_call itself, which keeps precedence,
• the request does not end with a user message. A request that ends with a tool message returns the result of a tool the client ran itself; forcing another call there could bounce tool calls between client and server.

The switch applies per request, so every new user turn starts with a tool call. It enforces that a tool is called, not which one or with which arguments.

Managing aliases

You can create, swap, and remove aliases from any of the management surfaces.

Web UI

Open Add Model and pick the Alias / Routing template, then set a name and a target. To re-point an existing alias, edit it and change the target.

REST API

• Create: POST /models/import
• Swap the target: PATCH /api/models/config-json/:name
• List all aliases: GET /api/aliases
• Delete: POST /models/delete/:name

Assistant and MCP

The LocalAI Assistant (and the MCP server) expose the same operations as tools: set_alias, list_aliases, and delete_model.

{{% notice note %}} You cannot turn an existing real model into an alias. If you run set_alias (or PATCH /api/models/config-json/:name) against a name that is already a real, non-alias model, the request is rejected. An alias is a pure redirect, so it must not carry a backend or parameters.model; a real model does, and merging an alias onto it produces an invalid config that validation refuses with alias config ... must not set backend or parameters.model. This is intentional: it stops a stray set_alias call from clobbering a model that is serving.

To add an alias, point a new name at the target instead of reusing an existing model's name. Re-pointing an existing alias at a different target is fully supported and is the live-swap path: the alias config has no backend of its own, so swapping its target stays a valid pure redirect. {{% /notice %}}

Aliases as deployment slots (distributed mode)

In [distributed mode]({{%relref "features/distributed-mode" %}}) an alias can carry a scheduling rule. POST /api/nodes/scheduling accepts an alias for model_name, and the rule then governs whatever model the alias points at:

curl -X POST http://frontend:8080/api/nodes/scheduling \
  -H "Content-Type: application/json" \
  -d '{"model_name": "production", "node_selector": {"tier": "gpu"}, "min_replicas": 2}'

Re-point production and the placement policy follows it, so the alias behaves as a stable slot whose contents you can swap. Because a replica is shared by every name that resolves to it, only one rule may govern a given model at a time. See [Scheduling a model alias]({{%relref "features/distributed-mode" %}}#scheduling-a-model-alias).

Limits

Aliases are a static 1:1 redirect; a profile block changes only the fields listed above, not the model or its loading options. For classifier-based or load-balanced selection across several downstream models, use the intelligent router in the [Middleware]({{%relref "operations/middleware" %}}) feature instead.