diff --git a/README.ja.md b/README.ja.md
index e81909a..d17358e 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -115,6 +115,8 @@ bot (`sender.login` が `[bot]` で終わる) と trim 後 10 文字未満の bo
 | `since` | ISO 8601 文字列 | `updated_at >= since` の結果だけを残します。 |
 | `until` | ISO 8601 文字列 | `updated_at < until` の結果だけを残します。 |
 | `include_content` | boolean | 上位 doc 結果に本文を inline する (既定 `false`)。 |
+| `graph_expand` | boolean | opt-in の GraphRAG 拡張（search モードのみ）。`true` のとき fusion 後の上位結果を seed に Decision-Structure の mention グラフ（D1 `doc_edges`）を辿り、関連 wiki ページを `graph_hop` / `graph_from` 付きで末尾に追加。既定 `false` は標準ハイブリッド検索とバイト単位で同一（グラフ未参照）。 |
+| `graph_hops` | number | `graph_expand` のグラフ探索深度（1 または 2、既定 1）。`graph_expand` が `false` のときは無視。 |
 
 #### `type` 値
 
diff --git a/README.md b/README.md
index 4880328..0d26b13 100644
--- a/README.md
+++ b/README.md
@@ -115,6 +115,8 @@ Bot-authored comments (`sender.login` ending in `[bot]`) and comments shorter th
 | `since` | ISO 8601 string | Keep only results with `updated_at >= since`. |
 | `until` | ISO 8601 string | Keep only results with `updated_at < until`. |
 | `include_content` | boolean | Inline raw content on top doc results (default `false`). |
+| `graph_expand` | boolean | Opt-in GraphRAG expansion (search mode only). When `true`, after fusion the top results seed a traversal of the Decision-Structure mention graph (D1 `doc_edges`); related wiki pages are appended tagged `graph_hop` / `graph_from`. Default `false` = byte-identical to standard hybrid retrieval (no graph read). |
+| `graph_hops` | number | Graph traversal depth for `graph_expand` (1 or 2, default 1). Ignored when `graph_expand` is `false`. |
 
 #### `type` values
 
@@ -124,6 +126,7 @@ Bot-authored comments (`sender.login` ending in `[bot]`) and comments shorter th
 | `"pull_request"` | Pull request descriptions (title + body). |
 | `"release"` | Release notes (name + body). |
 | `"doc"` | Markdown documentation files. |
+| `"wiki_doc"` | GitHub Wiki pages (separate surface from repo docs; both co-exist). |
 | `"diff"` | Per-file commit diffs (commit message + file path + patch). |
 | `"issue_comment"` | Top-level comments on issues and PRs. |
 | `"pr_review"` | PR review bodies (`APPROVED` / `CHANGES_REQUESTED` / `COMMENTED`). |
diff --git a/mcp-server/README.md b/mcp-server/README.md
index b1968c6..b7cfb6e 100644
--- a/mcp-server/README.md
+++ b/mcp-server/README.md
@@ -92,7 +92,7 @@ A single consolidated tool, `search`, covers every retrieval mode. Earlier build
 
 | Tool | Description |
 |---|---|
-| `search` | Unified search across GitHub issues, pull requests, releases, repository documentation, **GitHub Wiki pages**, commit diffs, and comment / review surfaces. Three modes are selected by the combination of `query` and `sort`: (1) **hybrid semantic search** — dense BGE-M3 over Vectorize + sparse BM25 over D1 FTS5, fused via RRF, then re-scored with the `bge-reranker-base` cross-encoder; (2) **time-ordered activity scan** — leave `query` empty and set `sort` to `updated_desc` / `created_desc`, optionally narrowed with `since` / `until`; (3) **doc / wiki content fetch** — set `include_content: true` to inline raw markup on top `doc` and `wiki_doc` rows. Structured filters (`repo`, `state`, `labels`, `milestone`, `assignee`, `type`, `top_k`, `fusion`, `rerank`) apply in every mode. |
+| `search` | Unified search across GitHub issues, pull requests, releases, repository documentation, **GitHub Wiki pages**, commit diffs, and comment / review surfaces. Three modes are selected by the combination of `query` and `sort`: (1) **hybrid semantic search** — dense BGE-M3 over Vectorize + sparse BM25 over D1 FTS5, fused via RRF, then re-scored with the `bge-reranker-base` cross-encoder; (2) **time-ordered activity scan** — leave `query` empty and set `sort` to `updated_desc` / `created_desc`, optionally narrowed with `since` / `until`; (3) **doc / wiki content fetch** — set `include_content: true` to inline raw markup on top `doc` and `wiki_doc` rows. Structured filters (`repo`, `state`, `labels`, `milestone`, `assignee`, `type`, `top_k`, `fusion`, `rerank`) apply in every mode. Search mode also accepts an opt-in `graph_expand` (with `graph_hops`, 1 or 2) that performs a GraphRAG expansion over the Decision-Structure mention graph and appends related wiki entries; it is off by default. |
 
 The `type` filter accepts: `issue`, `pull_request`, `release`, `doc`, `wiki_doc`, `diff`, `issue_comment`, `pr_review`, `pr_review_comment`, or `all` (default).