docs(mcp): client registration (Claude Code / Desktop)

Documents MCP server setup for Claude Code (.mcp.json) and Claude Desktop
(claude_desktop_config.json), HTTP transport config, and available tools table.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -104,6 +104,72 @@ codex ask "<question>"          # optional LLM Q&A via Ollama
 
 ---
 
+## MCP Server (F-14)
+
+codex exposes its KB as read-only MCP tools for LLM clients (Claude Code, Claude Desktop, etc.).
+
+### Start (stdio)
+
+```bash
+# directly
+python -m codex.mcp_server
+
+# or via the installed script
+codex-mcp
+```
+
+### Client registration
+
+**Claude Code** — add to `.mcp.json` in your project root:
+
+```json
+{
+  "mcpServers": {
+    "codex": {
+      "command": "uv",
+      "args": ["run", "codex-mcp"],
+      "cwd": "/path/to/codex-py"
+    }
+  }
+}
+```
+
+**Claude Desktop** — add to `~/Library/Application Support/Claude/claude_desktop_config.json`:
+
+```json
+{
+  "mcpServers": {
+    "codex": {
+      "command": "uv",
+      "args": ["--directory", "/path/to/codex-py", "run", "codex-mcp"]
+    }
+  }
+}
+```
+
+### HTTP transport (optional, config-gated)
+
+```bash
+MCP_TRANSPORT=http MCP_AUTH_TOKEN=<secret> codex-mcp
+```
+
+HTTP transport requires `MCP_AUTH_TOKEN` — the server refuses to start without it.
+Requests must carry `Authorization: Bearer <token>`.
+
+### Available tools (read-only)
+
+| Tool | Description |
+|---|---|
+| `search` | Chunk-level hybrid search (dense BGE-M3) |
+| `ask` | RAG answer (returns "not available" until implemented) |
+| `wiki_read` | Compiled concept page (F-12) |
+| `wiki_list` | All concept pages + freshness |
+| `discover_leads` | Dangling-citation leads |
+| `provenance_verify` | Scan C++ sources for @cite tags |
+| `synthesis_browse` | Leads/conjectures from leads/ (F-13) |
+
+---
+
 ## Development
 
 ```bash