--- description: Use when calling LLM APIs through the liter-llm MCP server's 22 tools, and to decide when MCP beats the CLI or SDK. Covers the tool surface, the auto-installing launcher, and authentication. name: liter-llm-using-the-mcp-server --- # Using the MCP Server The `liter-llm` MCP server exposes 22 tools that mirror the proxy's REST endpoints, so an MCP-compatible client (Claude Code, Claude Desktop) can call 174 LLM providers as tools with no glue code. ## Standalone skill installation Installing this skill alone does not register an MCP server or include the plugin launcher. Install the CLI (for example, `brew install xberg-io/tap/liter-llm`), then configure your MCP client with `liter-llm mcp --transport stdio` as its stdio command. The full product plugin supplies registration where the runtime supports MCP. ## How it runs in this plugin The plugin auto-registers the server. Its command is the bundled launcher `scripts/mcp-launch.sh`, which execs `liter-llm mcp --transport stdio`. On first run the launcher resolves a `liter-llm` binary: it reuses one on `PATH`, then tries `npx`/`uvx`, then Homebrew, then downloads a prebuilt from the tool's latest GitHub release. Override with `LITER_LLM_LAUNCHER=auto|npx|uvx|brew|download`. To run it manually: ```bash liter-llm mcp --transport stdio # for Claude Code / Claude Desktop liter-llm mcp --transport http --port 3001 ``` ## Configure model routing Provider-backed tools use the proxy model registry. Create `liter-llm-proxy.toml` in the working directory, or pass `--config /absolute/path/liter-llm-proxy.toml` when launching: ```toml [[models]] name = "gpt-4o" provider_model = "openai/gpt-4o" ``` Supply `OPENAI_API_KEY` in the MCP process environment, then call `chat` using the configured name `gpt-4o`. `list_models` shows configured names; an unknown model is a request error. Missing credentials are also reported on provider-backed requests. Gemini filters host credentials: install with `--skip-settings` and configure the selected provider through `gemini extensions config liter-llm "OpenAI key"`. Local stdio does not need a separate proxy virtual key. ## The 22 tools Modality tools: `chat`, `embed`, `generate_image`, `speech`, `transcribe`, `moderate`, `rerank`, `search`, `ocr`. Model listing: `list_models`. File operations: `create_file`, `list_files`, `retrieve_file`, `delete_file`, `file_content`. Batch operations: `create_batch`, `list_batches`, `retrieve_batch`, `cancel_batch`. Responses API: `create_response`, `retrieve_response`, `cancel_response`. ## Authentication Local stdio trusts the invoking local client by default, so the registered command starts without extra proxy authentication configuration. Provider API keys still come from environment variables and are needed for provider-backed requests. To apply a restricted virtual key, configure `mcp.stdio_key_id`; an unknown key fails startup. Set `mcp.stdio_trust_local = false` to require an explicit virtual key. HTTP transport retains its authentication policy; the local stdio default does not disable HTTP authorization. ## When to prefer MCP over the CLI or SDK - **Prefer MCP** inside an agent session: the agent invokes tools directly, with no code to write or process to manage. - **Prefer the SDK** when building application software in a specific language. - **Prefer the proxy** when many apps or teams need a shared OpenAI-compatible endpoint with keys, budgets, and rate limits.