@agent-arc-status/adapter-mcp

Bridge Model Context Protocol progress notifications and Agent Arc Status Protocol events — both directions. @modelcontextprotocol/sdk is a peer dependency.

An MCP tool that runs for minutes is silent from MCP's perspective until it returns; emitting arc.status events from its progress notifications makes that in-flight work observable to humans and other agents.

import { mcpProgressNotifier, arcToMcpProgress } from "@agent-arc-status/adapter-mcp";

// MCP progress -> arc.status (attach where you receive notifications/progress):
const notify = mcpProgressNotifier(emit, { arcId, title: "reindex corpus" });
notify({ progressToken: token, progress: 3, total: 8, message: "shard 3 of 8" });

// arc.status -> MCP progress (to report an arc's progress over MCP):
const params = arcToMcpProgress(event, token);

| MCP concept | arc concept | |---|---| | progress / total | step / total (when positive integers) | | progress message | title | | a progress notification | a milestone event |

progress === total is a candidate for done only when the tool actually returns — progress alone is not an honest done (spec §6.5).