Connect Claude Code to tools via MCP changedmcp
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252252#### Server status detail
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254In `/mcp`, a server's menu, and the [`/plugin`](/docs/en/plugins) manager, a remote (HTTP or SSE) server you've used before can show a `cached` status such as `cached 2h ago · connects on first use · 5 tools`. Claude Code loaded the server's tool list from a previous session instead of connecting at startup, and it connects the server the first time Claude calls one of its tools. The tools are available from your first message, so you don't need to do anything. To make every server connect at startup instead, set [`MCP_DISCOVERY_CACHE=0`](/docs/en/env-vars). The discovery cache and its `cached` status require Claude Code v2.1.221 or later.
254In `/mcp`, including a server's menu there, and in the [`/plugin`](/docs/en/plugins) manager, a remote HTTP or SSE server you've used before can show a `cached` status such as `cached 2h ago · connects on first use · 5 tools`. Claude Code loaded the server's tool list from its discovery cache, saved in a previous session, instead of connecting at startup, and Claude Code connects the server the first time Claude calls one of the server's tools. The tools are available from your first message, so you don't need to do anything. The discovery cache and its `cached` status require Claude Code v2.1.221 or later.
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256The discovery cache is off by default unless a gradual rollout has enabled it for your account. Set [`MCP_DISCOVERY_CACHE=1`](/docs/en/env-vars) to turn it on, or `0` to keep it off even when the rollout has enabled it. Before v2.1.238, the cache was on by default.
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258Two actions in a server's menu in `/mcp` also affect that server's cache entry:
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260* **Reconnect**: on a `cached` server, Claude Code connects it now rather than on its first tool call and keeps the entry. On a connected or failed server, Claude Code reconnects it and also discards the entry.
261* **Clear authentication**: Claude Code revokes the server's authentication and also discards the entry.
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263After discarding the entry, Claude Code fetches the server's tool list from the server instead of from the cache.
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256265When a server's status is `✘ Failed to connect`, `claude mcp list` appends the failure detail to that status line, and `claude mcp get <name>` shows it on an `Issue:` line: the HTTP status or error code, plus any error text the server returned. The server's detail view in `/mcp` includes the same server-reported text in its `Issue:` row. Claude Code redacts credential-like text from this detail and never includes the expanded server URL, which can carry secrets. Claude Code appends no detail to a `✘ Connection error` status, because the exception text it would print there can embed that URL. Before v2.1.219, both commands showed only the bare failure status, without the status code or the server's error text.
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258267A remote server whose configuration has an empty `url` shows as `not configured` in `/mcp`, in `claude mcp list`, and in the [`/plugin`](/docs/en/plugins) manager, and Claude Code doesn't attempt to connect to it. A plugin can include a placeholder entry like this for a connector you configure later, so Claude Code doesn't report it as an error or a setup issue. The server's detail view in `/mcp` reads `No URL configured for this server`; set the entry's `url` to connect it. Before v2.1.208, Claude Code reported an empty `url` as a configuration issue with a prompt to reconnect.
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397406**Plugin MCP features**:
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399408* **Automatic lifecycle**: servers connect and disconnect at these points:
400 * At session startup, Claude Code connects the servers for enabled plugins automatically. In `/mcp`, a remote (HTTP or SSE) plugin server you've used before can show the [`cached` status](#managing-your-servers) instead; Claude Code connects it when Claude first calls one of its tools
409 * At session startup, Claude Code connects the servers for enabled plugins automatically. In `/mcp`, a remote (HTTP or SSE) plugin server you've used before can show the [`cached` status](#server-status-detail) instead; Claude Code connects it when Claude first calls one of its tools
401410 * If you enable or disable a plugin during a session, run `/reload-plugins` to connect or disconnect its MCP servers. When you reload, Claude Code keeps the live connections of plugin servers whose configuration is unchanged, and does the same when you [replace the session's MCP server list](/docs/en/agent-sdk/typescript#mcpsetserversresult) from the Agent SDK without naming them
402411 * In [web sessions](/docs/en/claude-code-on-the-web), an MCP call to a plugin server that isn't connected yet, such as right after an idle session wakes, starts the server on demand and waits for it to connect
403412* **Path placeholders**: `${CLAUDE_PLUGIN_ROOT}` resolves to the plugin's installation directory, `${CLAUDE_PLUGIN_DATA}` to its [persistent state](/docs/en/plugins-reference#persistent-data-directory) directory, and `${CLAUDE_PROJECT_DIR}` to the stable project root. Substitution applies to:
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12871296The `alwaysLoad` field is available on all server types. An MCP server can also mark individual tools as always-loaded by including `"anthropic/alwaysLoad": true` in the tool's `_meta` object, which has the same effect for that tool only.
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1289Setting `alwaysLoad: true` also makes startup wait for the server's tools, capped at the standard 5-second connect timeout, since they must be present when the first prompt is built. A remote server with a valid [`cached` entry](#managing-your-servers) supplies its tools from the cache without connecting, so it doesn't hold startup. Other servers connect in the background by default; set [`MCP_CONNECTION_NONBLOCKING=0`](/docs/en/env-vars) to make startup wait for them too.
1298Setting `alwaysLoad: true` also makes startup wait for the server's tools, capped at the standard 5-second connect timeout, since they must be present when the first prompt is built. A remote server with a valid [`cached` entry](#server-status-detail) supplies its tools from the cache without connecting, so it doesn't hold startup. Other servers connect in the background by default; set [`MCP_CONNECTION_NONBLOCKING=0`](/docs/en/env-vars) to make startup wait for them too.
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12911300## Use MCP prompts as commands
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