Codex Ollama Proxy

Codex Ollama Proxy

npm package

Use Ollama, OpenRouter, and other Responses API providers with Codex while preserving Codex plugins, MCP tools, tool_search, and apply_patch.

Codex normally sends plugins and MCP tools using OpenAI-specific namespace and dynamic-tool formats. Many custom providers reject or cannot interpret these formats, producing errors such as:

• unsupported call
• MCP tools are visible but never invoked
• tool_search aborts
• namespace tools are rejected
• apply_patch is returned in the wrong format

codex-ollama-proxy runs locally and translates these request and response shapes between Codex and the configured model provider.

This is unofficial and experimental. Codex internal tool formats can change, so the proxy may need updates as Codex changes.

Quick Start

npm install -g codex-ollama-proxy
codex-ollama-proxy init
codex-ollama-proxy install

The proxy listens on 127.0.0.1:11436 and forwards to the configured upstream Responses API server. By default, the upstream is local Ollama at http://127.0.0.1:11434/v1.

To pin a specific release, install from the npm tarball:

npm install -g https://registry.npmjs.org/codex-ollama-proxy/-/codex-ollama-proxy-0.3.3.tgz

Use Codex Plugins With Ollama

The default upstream is Ollama's local OpenAI-compatible Responses API:

codex-ollama-proxy upstream --url "http://127.0.0.1:11434/v1"
codex-ollama-proxy restart

The proxy flattens Codex namespace/plugin tools into model-callable functions, then maps the resulting calls back to the format Codex expects.

Use Codex Plugins With OpenRouter

Point the upstream at a Responses-compatible OpenRouter endpoint and provide a bearer token:

codex-ollama-proxy upstream --url "https://openrouter.ai/api/v1" --api-key "KEY"
codex-ollama-proxy restart

The upstream must expose a compatible Responses API. Chat Completions-only APIs (/v1/chat/completions) need a separate adapter and are not supported by this setting alone.

Configure Upstream Responses API

Set or inspect the upstream Responses API server:

codex-ollama-proxy upstream --url "https://example.com/v1" --api-key "KEY"
codex-ollama-proxy upstream --status

Separate text and image models:

codex-ollama-proxy route --text-model "TEXT_MODEL" --image-model "IMAGE_MODEL" --auto-image
codex-ollama-proxy switch ollama --model "TEXT_MODEL"

One model for both:

codex-ollama-proxy route --text-model "MODEL" --image-model "MODEL" --auto-image
codex-ollama-proxy switch ollama --model "MODEL"

After switching, restart Codex or open a fresh thread.

Fix MCP Unsupported Call Errors In Codex

Codex app plugins and MCP tools can arrive as namespace tools or dynamically loaded tools. Local/custom providers often cannot invoke those shapes directly. The proxy rewrites those tools into ordinary function tools for the model, then restores the calls for Codex.

Fix Codex Namespace Tool Compatibility

Namespace tools are flattened into names that model providers can call. For example, a namespace tool can be exposed as a function-like tool and then split back into the namespace/name pair expected by Codex.

Fix tool_search With Custom Providers

The proxy keeps Codex tool_search flows usable by preserving deferred tool discovery and mapping returned tool calls back into Codex-compatible shapes.

Recent Codex/Desktop builds can expose tool_search as a native managed tool:

{ "type": "tool_search", "execution": "client" }

Many custom providers do not treat that native item as callable. The proxy rewrites it into a normal function tool named tool_search for the model, then maps the model's function_call back into Codex's native tool_search_call.

If Codex omits the native tool_search item from a turn, the proxy still injects the same function shim so local/custom models can discover deferred tools consistently.

When tool_search returns deferred MCP/plugin namespace tools, the proxy also exposes those discovered tools as top-level callable functions on the follow-up model request. For example, a Storefront Builder tool returned by search as mcp__storefront_builder.list_storefront_build_sessions is made callable to the model as mcp__storefront_builder__list_storefront_build_sessions, then translated back to Codex as:

{
  "type": "function_call",
  "namespace": "mcp__storefront_builder",
  "name": "list_storefront_build_sessions"
}

How apply_patch Translation Works

Codex may expose apply_patch as a custom/freeform tool. The proxy preserves the freeform custom tool behavior for Codex while making the surrounding tool list easier for local or custom Responses API providers to handle.

Supported Providers

• Ollama-compatible Responses API servers
• OpenRouter or other custom providers that expose a compatible Responses API
• Local shims that accept POST /v1/responses

Chat Completions-only providers are not supported by upstream URL configuration alone.

Known Limitations

• This package is not affiliated with OpenAI.
• Codex internal tool schemas can change.
• Provider support depends on how closely the upstream matches the Responses API.
• Web search falls back from Ollama cloud search, to local Ollama search, to DuckDuckGo HTML search.

Codex Skill

Copy this skill link into Codex:

https://raw.githubusercontent.com/bharat2808/codex-ollama-proxy/main/skills/codex-ollama-proxy/SKILL.md

Then ask:

Install this skill and use it to set up codex-ollama-proxy.

Useful Commands

codex-ollama-proxy status
codex-ollama-proxy upstream --status
codex-ollama-proxy logs --tail 100
codex-ollama-proxy restart
codex-ollama-proxy switch openai

Uninstall

codex-ollama-proxy switch openai
codex-ollama-proxy uninstall
npm uninstall -g codex-ollama-proxy

Files

Runtime config and logs:

~/.codex/ollama-shape-proxy/proxy-models.toml
~/.codex/ollama-shape-proxy/proxy.log

Debug flags are off by default:

verbose_tools = false
log_upstream_body = false

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: bharat2808
• Source: bharat2808/codex-ollama-proxy
• License: MIT
• Homepage: https://www.npmjs.com/package/codex-ollama-proxy

Install and usage instructions live in the source repository linked above.