> ## Documentation Index > Fetch the complete documentation index at: https://docs.mcp-use.com/llms.txt > Use this file to discover all available pages before exploring further. # CLI Client > Connect to HTTP MCP servers, call tools, read resources, get prompts, manage OAuth, and produce parseable JSON from the terminal. Use `mcp-use client` to test or automate an HTTP MCP server from the terminal. Save a server under a name, then use that name for every tool, resource, prompt, and auth command. For the complete command and flag catalog, see the [CLI reference](/v2/typescript/api-reference/cli-reference#client). ## Connect and call a tool Run the CLI with `npx`, or install `mcp-use` in your project. ```bash theme={null} npx mcp-use client connect dev http://localhost:3000/mcp npx mcp-use client dev tools list npx mcp-use client dev tools call get-weather city=Tokyo ``` `connect` supports HTTP and HTTPS MCP URLs. It verifies the connection before saving it. The CLI stores saved server metadata under `~/.mcp-use/client/`. List or remove saved servers with these commands: ```bash theme={null} npx mcp-use client list npx mcp-use client remove dev ``` ## Choose a protocol mode The default `--protocol auto` mode prefers the modern MCP wire and falls back to the legacy wire when the server does not support modern negotiation. Use `legacy` or `modern` when you need strict compatibility testing: ```bash theme={null} npx mcp-use client connect old-server https://old.example.com/mcp \ --protocol legacy npx mcp-use client connect modern-server https://modern.example.com/mcp \ --protocol modern ``` `legacy` uses only the legacy wire. `modern` uses the stateless, sessionless modern wire with no fallback. ## Authenticate with OAuth When a server requires OAuth in an interactive terminal, the CLI displays this prompt: ```text theme={null} This server requires OAuth. Press Enter to open your browser. ``` Press Enter to open the authorization page. The command keeps waiting for the loopback callback, then verifies and saves the connection. ### Mixed auth A mixed-auth server lets `connect` succeed anonymously, then protects only some operations. When the server advertises OAuth through protected-resource metadata, the CLI saves it normally and prints: ```text theme={null} Connected and saved prod. This server is using mixed auth. Public tools are available now; run `mcp-use client prod auth login` to authenticate. ``` You can keep using public tools and let the first wire-level OAuth challenge start authorization later, or authenticate before calling protected operations: ```bash theme={null} npx mcp-use client prod auth login ``` After interactive authorization, the CLI retries the challenged operation once. It does not infer OAuth from tool-level `isError` results or error text. Use `--no-open` to authenticate without launching a browser: ```bash theme={null} npx mcp-use client connect prod https://mcp.example.com/mcp --no-open ``` With `--no-open` or non-interactive human output, the CLI never prompts or opens a browser. It prints a state-free local loopback launcher URL and continues waiting for the callback. Open that local URL yourself; it redirects to the provider without putting the provider URL or OAuth state in terminal output. Under `--json`, the CLI never prints the authorization URL or OAuth state and never waits for consent. If fresh authorization is required, it exits with `oauth_interaction_required` and provides an interactive retry command in `error.details.nextSteps`. Use `--no-oauth` for a public server or when an authorization challenge should fail instead of starting OAuth. Repeated `-H` or `--header` options add static request headers. ```bash theme={null} npx mcp-use client connect public https://mcp.example.com/mcp --no-oauth npx mcp-use client connect private https://mcp.example.com/mcp \ -H "Authorization: Bearer $TOKEN" --no-oauth ``` Authenticate, check, or clear saved OAuth credentials with auth commands: ```bash theme={null} npx mcp-use client prod auth login npx mcp-use client prod auth status npx mcp-use client prod auth logout ``` `auth login` starts OAuth for a saved server. `auth logout` removes OAuth material but keeps the saved server and its non-OAuth connection metadata. Connection URLs are stored exactly for transport use, but CLI results redact URL userinfo, query values, and fragments so signed URLs and embedded credentials are not copied into logs. ## Call tools List tools, inspect a tool schema, then call the tool with its required inputs. ```bash theme={null} npx mcp-use client dev tools list npx mcp-use client dev tools describe get-weather npx mcp-use client dev tools call get-weather city=Tokyo ``` Tool and prompt arguments accept `key=value` pairs. Use `key:=` for typed or nested values, or pass one JSON object. ```bash theme={null} npx mcp-use client dev tools call search query=shoes limit:=5 npx mcp-use client dev tools call search filters:='{"color":"black","inStock":true}' npx mcp-use client dev tools call search '{"query":"shoes","limit":5}' ``` Use `--timeout ` for slow tools. The default is `30000` milliseconds. ```bash theme={null} npx mcp-use client dev tools call generate-report topic=sales --timeout 60000 ``` ## Read resources Resources are server-provided content identified by URI. List resources, then read the URI you need. ```bash theme={null} npx mcp-use client dev resources list npx mcp-use client dev resources read "file:///tmp/data.json" ``` ## Get prompts Prompts are reusable message templates exposed by the server. Prompt arguments use the same forms as tool arguments. ```bash theme={null} npx mcp-use client dev prompts list npx mcp-use client dev prompts get greeting name=Alice npx mcp-use client dev prompts get greeting '{"name":"Alice"}' ``` ## Produce parseable JSON Every client command documented with `--json` accepts it anywhere after `client`. The following forms are equivalent: ```bash theme={null} npx mcp-use client --json dev tools list npx mcp-use client dev --json tools list npx mcp-use client dev tools list --json ``` Successful commands write exactly one JSON value followed by a newline to stdout. Calls, resource reads, and prompt gets return the raw MCP result envelope. Lists return arrays. Errors write one envelope to stderr and do not write a result to stdout: ```json theme={null} { "error": { "code": "usage_error", "message": "Tool not found: missing" } } ``` OAuth authorization URLs and dependency-install status are operational messages on stderr, so stdout remains parseable under `--json`. ```bash theme={null} #!/usr/bin/env bash set -euo pipefail npx mcp-use client connect dev http://localhost:3000/mcp --no-oauth --json >/dev/null npx mcp-use client dev tools list --json | jq -r '.[].name' npx mcp-use client dev tools call get-weather city=Tokyo --json | jq '.content' ``` ## Troubleshoot commands * `Unknown saved server: `: run `npx mcp-use client list`, or reconnect with `npx mcp-use client connect `. * `Tool not found: `: run `tools list` against the same saved server. * `protocol_mismatch`: reconnect with `--protocol auto`, or choose the protocol mode the server supports. * An OAuth command waits without opening a browser: open the authorization URL printed to stderr, then complete authorization before the configured timeout. * A tool returns an error: under `--json`, inspect `error.details` for the original MCP tool result. For exhaustive command shapes, flags, and storage details, use the [CLI reference](/v2/typescript/api-reference/cli-reference#client).