Connect Claude Code to tools via MCP changedmcp
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441441
442442### Plugin-provided MCP servers
443443
444[Plugins](/docs/en/plugins/overview) can bundle MCP servers that provide tools and integrations when you enable the plugin. Plugin MCP servers work identically to user-configured servers.
444[Plugins](/docs/en/plugins/overview) can bundle MCP servers that provide tools and integrations when you enable the plugin.
445445
446446**How plugin MCP servers work**:
447447
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14471447
14481448To change the limit for every MCP server in your session, set [`CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH`](/docs/en/env-vars#variables) to a number of characters. This variable requires Claude Code v2.1.280 or later.
14491449
1450<h4 id="per-tool-alwaysload">
1451 Mark a tool to load upfront or stay deferred
1452</h4>
1453
1454To control how one of your server's tools loads, set `"anthropic/alwaysLoad"` in that tool's `_meta` object. The person who adds your server to Claude Code can also set [`alwaysLoad`](#exempt-a-server-from-deferral) for the whole server in their configuration, and their setting can override yours:
1455
1456| Your tool's value | What happens |
1457| :- | :- |
1458| `true` | The tool loads upfront. Startup doesn't wait for your server because of this value. The person configuring your server can still [defer all of its tools](#defer-a-servers-tools) |
1459| `false` | The tool stays deferred when their configuration sets `"alwaysLoad": true`. This applies when your server is passed with [`--mcp-config`](/docs/en/cli-reference#cli-flags), supplied by an [Agent SDK application](/docs/en/agent-sdk/mcp#in-code), or provided by a [plugin](#plugin-provided-mcp-servers). On other servers the tool loads upfront. Requires Claude Code v2.1.285 or later |
1460
1461The following `tools/list` entry asks for one tool to load upfront:
1462
1463```json theme={null}
1464{
1465 "name": "search_tickets",
1466 "description": "Searches the ticket tracker by keyword",
1467 "_meta": {
1468 "anthropic/alwaysLoad": true
1469 }
1470}
1471```
1472
14501473### Configure tool search
14511474
14521475Tool search is enabled by default: MCP tools are deferred and discovered on demand. Claude Code disables it when `ANTHROPIC_BASE_URL` points to a non-first-party host, since most proxies don't forward `tool_reference` blocks. Set `ENABLE_TOOL_SEARCH` explicitly to override that fallback.
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14941517
14951518### Exempt a server from deferral
14961519
1497If a server's tools should always be visible to Claude without a search step, set `alwaysLoad` to `true` in that server's configuration. Every tool from that server then loads into context at session start regardless of the `ENABLE_TOOL_SEARCH` setting. Use this for a small number of tools that Claude needs on every turn, since each upfront tool consumes context that would otherwise be available for your conversation.
1520If a server's tools should always be visible to Claude without a search step, set `alwaysLoad` to `true` in that server's configuration. The server's tools then load into context regardless of the `ENABLE_TOOL_SEARCH` setting. Use this for a small number of tools that Claude needs on every turn, since each upfront tool consumes context that would otherwise be available for your conversation.
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14991522The following `.mcp.json` entry exempts one HTTP server while leaving other servers deferred:
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15101533}
15111534```
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1513The `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.
1536The `alwaysLoad` field is available on all server types.
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15151538Setting `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.
1539
1540<h3 id="defer-a-servers-tools">
1541 Defer a server's tools
1542</h3>
1543
1544To keep all of a server's tools behind tool search, set `"alwaysLoad": false` in that server's entry in your MCP configuration. That includes tools that the server's author has [marked to load upfront](#per-tool-alwaysload). If you leave `alwaysLoad` out, those marked tools load upfront. Requires Claude Code v2.1.287 or later.
15161545
15171546## Use MCP prompts as commands
15181547
No line in this hunk matches that.