Tin Chi Lo f776ea7f9b feat(mcp): per-server outcomes for aggregate tools/list and truthful single-server REST statuses ... The aggregate MCP tools/list absorbed every per-server failure (upstream 401/403/5xx, timeouts, network errors) into that server contributing zero tools, making a broken upstream indistinguishable from a healthy server with no tools; the single-server REST list masked the same failures as {"tools": [], "error": null, "message": "Successfully retrieved tools"} Phase 2 of the MCP error-handling framework (LIT-4419): the manager fetch hops now raise a classified MCPServerListError (faults/list_outcomes.py: total classifier, frozen outcome values) instead of returning [], and each boundary applies the relay-vs-absorb policy matrix. The aggregate keeps serving the healthy subset but records each server's outcome, surfaced on the tools/list result _meta under litellm.ai/server_outcomes (the SDK passes a ListToolsResult through unwrapped) and in spend logs as per_server_list_outcomes. Single-server REST requests relay truthful statuses (unreachable/upstream_error 502, timeout 504, internal 500) and access denials now surface as real 403s instead of 200 unexpected_error bodies; upstream 403s surface through MCPUpstreamAuthError like 401s. Outcome wire values carry category and status code only, never upstream prose Resolves LIT-4421		2026-07-14 20:03:56 -07:00
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mcp_server	feat(mcp): per-server outcomes for aggregate tools/list and truthful single-server REST statuses	2026-07-14 20:03:56 -07:00