diff --git a/bridge/tools.js b/bridge/tools.js
index 6b66bf4..26f4a03 100644
--- a/bridge/tools.js
+++ b/bridge/tools.js
@@ -43,11 +43,11 @@ function withLineNumbers(lines, startLine) {
 // 工具元数据（GET /tools 的数据源；扩展据此生成协议消息，防两端清单漂移）
 // ---------------------------------------------------------------------------
 const TOOL_DEFS = [
-  { name: 'dsh_tree', description: 'List directory tree (skips node_modules/.git)', params: { path: 'string?', depth: 'int? default 3' } },
-  { name: 'dsh_read', description: 'Read a text file fragment (1-based lines with line numbers; returns sha256 for edit verification)', params: { path: 'string', offset: 'int? default 1', limit: 'int? default 200' } },
+  { name: 'dsh_tree', description: 'List directory tree (skips node_modules/.git). ifMoreThan: return meta only if entries exceed this.', params: { path: 'string?', depth: 'int? default 3', ifMoreThan: 'int? if entries > N, return meta instead of tree' } },
+  { name: 'dsh_read', description: 'Read a text file fragment (1-based lines with line numbers; returns sha256 for edit verification). maxBytes: return meta only if file exceeds this.', params: { path: 'string', offset: 'int? default 1', limit: 'int? default 200', maxBytes: 'int? if file size > N, return meta instead of content' } },
   { name: 'dsh_write', description: 'Write file (creates parent dirs). mode: overwrite (default) | create (fail if exists) | append (append to existing)', params: { path: 'string', content: 'string', mode: 'string? overwrite|create|append, default overwrite', expectedSha256: 'string? reject if current content differs (stale-write guard)' } },
   { name: 'dsh_edit', description: 'Replace a unique fragment in a file', params: { path: 'string', oldText: 'string', newText: 'string', expectedSha256: 'string? sha256 from dsh_read; reject if file changed' } },
-  { name: 'dsh_search', description: 'Search file contents (plain or regex)', params: { query: 'string', path: 'string?', regex: 'bool?', caseSensitive: 'bool?', maxResults: 'int? default 50' } },
+  { name: 'dsh_search', description: 'Search file contents (plain or regex). ifMoreThan: return meta only if matches exceed this.', params: { query: 'string', path: 'string?', regex: 'bool?', caseSensitive: 'bool?', maxResults: 'int? default 50', ifMoreThan: 'int? if matches > N, return meta instead of matches' } },
   { name: 'dsh_bash', description: 'Run a whitelisted command in the workspace', params: { command: 'string', timeoutMs: 'int? default 20000' } },
   { name: 'dsh_script', description: 'Run a named python/mjs script with declared inputs/outputs. Requires user confirm. inputs are sha-checked before/after, outputs are verified after.', params: { name: 'string snake_case', language: 'python|mjs', code: 'string source', inputs: 'string[]? relative paths that must exist before run', outputs: 'string[]? relative paths verified after run', timeoutMs: 'int? default bashTimeoutMs' } },
   { name: 'dsh_git_status', description: 'git status (read-only porcelain)', params: { path: 'string?' } },
@@ -213,6 +213,15 @@ function toolTree(ctx, args) {
   const base = st.isDirectory() ? relPath : path.dirname(relPath);
   const out = { lines: [], count: 0, maxDepth: Math.min(Number(args.depth) || 3, 8), truncated: false };
   walkTree(root, base === '.' ? '' : base, 0, out);
+  const ifMoreThan = args.ifMoreThan !== undefined ? Math.max(1, Number(args.ifMoreThan)) : null;
+  if (ifMoreThan !== null && out.count > ifMoreThan) {
+    return {
+      tooMany: true,
+      count: out.count,
+      ifMoreThan,
+      hint: `Tree has ${out.count} entries (> ifMoreThan ${ifMoreThan}). Reduce depth, narrow path, or raise ifMoreThan.`,
+    };
+  }
   return {
     tree: out.lines.join('\n') || '(empty dir)',
     fileCount: out.count,
@@ -229,6 +238,17 @@ function toolRead(ctx, args) {
     throw new ToolError('E_ARGS_INVALID', `File not found: ${posixRel}`);
   }
   if (st.isDirectory()) throw new ToolError('E_ARGS_INVALID', `Target is a directory, use dsh_tree: ${posixRel}`);
+  // Explicit size estimate: if model declared maxBytes and file exceeds it, return meta only.
+  const maxBytes = args.maxBytes !== undefined ? Math.max(1, Number(args.maxBytes)) : null;
+  if (maxBytes !== null && st.size > maxBytes) {
+    return {
+      file: posixRel,
+      tooLarge: true,
+      size: st.size,
+      maxBytes,
+      hint: `File is ${st.size} bytes (> maxBytes ${maxBytes}). Use offset/limit for a range, dsh_search for content, or raise maxBytes.`,
+    };
+  }
   // 整读上限 READ_MAX_BYTES；带 offset/limit 范围读取时放宽到 RANGE_SCAN_MAX_BYTES（CodexPro 模式）
   const hasRange = args.offset !== undefined || args.limit !== undefined;
   if (st.size > READ_MAX_BYTES && !(hasRange && st.size <= RANGE_SCAN_MAX_BYTES)) {
@@ -363,6 +383,8 @@ function toolSearch(ctx, args) {
   const baseRel = st.isDirectory() ? (relPath === '.' ? '' : relPath.replace(/\\/g, '/')) : path.dirname(relPath).replace(/\\/g, '/');
 
   const maxResults = Math.min(Math.max(1, Number(args.maxResults) || 50), 200);
+  const ifMoreThan = args.ifMoreThan !== undefined ? Math.max(1, Number(args.ifMoreThan)) : null;
+  const effMax = ifMoreThan !== null ? Math.min(maxResults, ifMoreThan + 1) : maxResults;
   let matcher;
   if (args.regex) {
     let re;
@@ -376,13 +398,13 @@ function toolSearch(ctx, args) {
     const needle = args.caseSensitive ? args.query : args.query.toLowerCase();
     matcher = (line) => (args.caseSensitive ? line.includes(needle) : line.toLowerCase().includes(needle));
   }
-  const out = { matches: [], maxResults, filesScanned: 0 };
+  const out = { matches: [], maxResults: effMax, filesScanned: 0 };
   if (st.isFile()) {
     // 单文件搜索
     const buf = fs.readFileSync(abs);
     if (!sniffBinary(buf)) {
       buf.toString('utf8').split('\n').forEach((line, i) => {
-        if (out.matches.length < maxResults && matcher(line)) {
+        if (out.matches.length < effMax && matcher(line)) {
           out.matches.push({ file: baseRel ? `${baseRel}/${path.basename(abs)}` : path.basename(abs), line: i + 1, text: line.slice(0, 240) });
         }
       });
@@ -391,7 +413,16 @@ function toolSearch(ctx, args) {
   } else {
     searchWalk(baseDir, baseRel, matcher, out);
   }
-  return { matches: out.matches, truncated: out.matches.length >= maxResults, filesScanned: out.filesScanned };
+  if (ifMoreThan !== null && out.matches.length > ifMoreThan) {
+    return {
+      tooMany: true,
+      count: out.matches.length,
+      ifMoreThan,
+      filesScanned: out.filesScanned,
+      hint: `Search returned > ${ifMoreThan} matches. Refine query, narrow path, or raise ifMoreThan.`,
+    };
+  }
+  return { matches: out.matches, truncated: out.matches.length >= effMax, filesScanned: out.filesScanned };
 }
 
 function runCaptured(cmd, cmdArgs, cwd, timeoutMs, maxOut, opts) {