Unavailable sources¶
Optional MCP servers (Context7, Tavily, code-review-graph, tilth) are not always present. Fallbacks exist, but evidence quality drops — surface that honestly.
Per-source fallbacks¶
| Source | If MCP missing | Confidence impact |
|---|---|---|
| Context7 | Read repo docs, package README, vendor pages, then web search | Cap at speculating for version-specific questions |
| Tavily | WebFetch (host fetch) for verify/extract; host web search or user-provided links for discovery | Cap at speculating when freshness matters |
Codebase (cheez-*) |
Fall back to Serena or LSP, sg, ripgrep, find, and targeted reads |
Cap at speculating when local precedent is central |
| code-review-graph (full tool list in README → Optional tools) | Use tilth_deps + cheez-search callers (tilth_search kind: "callers") for blast radius; skip cross-repo, semantic search, and architecture framing |
Cap at speculating for cross-repo or large-architecture questions |
GitHub (gh) |
Note absence; user-supplied URLs are acceptable | Skip with a confidence note |
Reporting an unavailable source¶
Once per session, after the routing block:
UNAVAILABLE: Tavily MCP not loaded. Falling back to WebFetch for link verification and host web search for discovery.
Freshness-sensitive answers will be capped at `speculating`.
Do not retry. Do not silently swap to a different question. The cap is real and the user reads the same line you do.
When to refuse instead of fall back¶
Stop and ask the user when: - The question explicitly demands a source that is unavailable (e.g., "use Context7 for this"). - All routed sources are unavailable. - A fallback would require fabricating information.