Confusing search_files function description leads to misunderstanding of its purpose.

Rename "search_files" to search_files_by_name.
Add new "search_file_contents" function.
Add descriptions to help the LLM understand the fields.
Support single file search.
Support glob pattern for search by file name.
Rename 'pattern' argument to 'searchText'. Sometimes the name 'pattern' caused
Claude to pass a regex even though it was processed as a simple substring match.

Author: sebastien-rosset

src/filesystem/README.md

@@ -7,7 +7,8 @@ Node.js server implementing Model Context Protocol (MCP) for filesystem operatio
 - Read/write files
 - Create/list/delete directories
 - Move files/directories
-- Search files
+- Search for files by name
+- Search within file contents (grep-like functionality)
 - Get file metadata
 - Dynamic directory access control via [Roots](https://modelcontextprotocol.io/docs/learn/client-concepts#roots)
 
@@ -130,14 +131,27 @@ The server's directory access control follows this flow:
     - `destination` (string)
   - Fails if destination exists
 
-- **search_files**
-  - Recursively search for files/directories
+- **search_files_by_name**
+  - Find files and directories whose names match a pattern
   - Inputs:
     - `path` (string): Starting directory
-    - `pattern` (string): Search pattern
+    - `pattern` (string): Name pattern to match
     - `excludePatterns` (string[]): Exclude any patterns. Glob formats are supported.
   - Case-insensitive matching
-  - Returns full paths to matches
+  - Returns full paths to matching files/directories
+
+- **search_file_contents**
+  - Search for text patterns within file contents (similar to grep)
+  - Inputs:
+    - `path` (string): Starting directory or specific file
+    - `searchText` (string): Text to search for - supports plain text substring matching or regex if useRegex is true
+    - `useRegex` (boolean): Whether to interpret searchText as a regular expression (default: false)
+    - `caseSensitive` (boolean): Enable case-sensitive search (default: false)
+    - `maxResults` (number): Maximum number of results to return (default: 100)
+    - `contextLines` (number): Number of context lines to show around matches (default: 2)
+    - `includePatterns` (string[]): Glob patterns for paths to include in search (e.g., ["**/*.js", "**/*.ts"])
+    - `excludePatterns` (string[]): Glob patterns for paths to exclude from search (e.g., ["node_modules/**", "*.test.ts"])
+  - Returns matching files with line numbers, matched text, and context
 
 - **get_file_info**
   - Get detailed file/directory metadata