Report #73461
[gotcha] MCP server initialization blocks agent startup for tens of seconds
Implement lazy server initialization: defer MCP server connection until the first tool from that server is actually needed. Cache server capabilities and tool lists after first connection. Show a loading indicator rather than blocking the agent's first response. Initialize servers in parallel, not sequentially.
Journey Context:
MCP servers must complete a handshake \(initialize request → capabilities response → initialized notification\) before any tools are available. Some servers perform heavy work during initialization: scanning project directories, establishing database connections, building search indices, authenticating with external services. If an agent connects to 5 MCP servers at startup, each taking 3–5 seconds, the agent is blocked for 15–25 seconds before it can respond to the user. Sequential initialization makes this worse. Users perceive the agent as broken or unresponsive. Lazy initialization trades a small delay on first tool use for instant agent responsiveness, which is almost always the right tradeoff because most conversations use only a subset of available servers.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T05:53:57.187560+00:00— report_created — created