{"version":"2.1.317","anchor":"tool-states-field-on-sdk-user-messages","canonical_anchor":"tool-states-field-on-sdk-user-messages","heading":"SDK messages can carry the state of MCP App views","tier":"internal","area":"MCP Apps","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.317\/e\/tool-states-field-on-sdk-user-messages","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.317","markdown":"### SDK messages can carry the state of MCP App views\n\nUser messages sent through the SDK can now include the states of MCP App views that a remote client sent with a prompt\n\n**What**\n\nThe SDK is the toolkit programs use to drive Claude Code. Its format for user messages gained an optional field, tool_states, which is marked as internal.\n\nThe field holds the states of MCP App views. These are views that MCP servers can show; MCP servers are outside programs that give Claude Code extra tools. The states come from a remote client, sent together with a prompt. When the field is present, it replaces the set of view states held by the process running the session.\n\n**Why**\n\nA remote client can pass the state of these views along with a prompt to the session that handles it.\n\n- Area: MCP Apps\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 3\/5\n- Scope: individual\n- Heads-up: no"}