Filesystem MCP Server

Secure filesystem MCP server for reading, writing, searching, diffing, and patching files.

Overview
Key Features
Quick Start — Docker · CLI Usage
Client Configuration
Use Cases
Architecture
MCP Surface — Tools · Resources · Prompts
MCP Capabilities — Tool Annotations · Structured Output
Configuration — HTTP & Auth · File Size Limits · Access Control · Output & Inline Limits · Tasks · Logging & Diagnostics · Performance
HTTP Endpoints
Security
Development
Troubleshooting
Credits
Contributing and License

Overview

A secure, production-ready Model Context Protocol server that gives AI assistants controlled access to the local filesystem. All operations are sandboxed to explicitly allowed directories with path traversal prevention, sensitive file blocking, and optional Bearer token authentication.

Supports stdio (default) and Node Streamable HTTP transport. HTTP sessions are implemented with isolated per-session server state. The HTTP transport is stateful by default and currently non-resumable; it does not persist an event store for Last-Event-ID replay.

Key Features

18 filesystem tools — read, write, search, diff, patch, hash, and bulk operations with structured output schemas
Security-first — path validation, symlink escape prevention, sensitive file denylist, localhost-only CORS, Host header validation for loopback HTTP binds, optional API key auth
Dual transport — stdio for local use, Node Streamable HTTP for networked/multi-session deployments
Structured output — all tools return typed outputSchema / structuredContent for reliable LLM parsing
Self-documenting — 6 built-in resources (internal://instructions, internal://tool-catalog, etc.) and 4 built-in prompts (get-help, compare-files, analyze-path, get-tool-help)

Requirements

Node.js >= 24

Quick Start

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Docker

docker run -i --rm -v /path/to/project:/workspace:ro ghcr.io/j0hanz/filesystem-mcp /workspace

Or using Docker Compose:

services:
 filesystem-mcp:
 build: .
 stdin_open: true
 volumes:
 - ./:/projects/workspace:ro
 command: ['/projects/workspace']

CLI Usage

filesystem-mcp [options] [allowedDirs...]

Arguments:
 allowedDirs Directories the server can access

Options:
 --allow-cwd Allow the current working directory as an additional root
 --port <number> Enable HTTP transport on the given port
 -v, --version Display server version
 -h, --help Display help

Examples:
 $ npx @j0hanz/filesystem-mcp@latest /path/to/project
 $ npx @j0hanz/filesystem-mcp@latest --allow-cwd
 $ npx @j0hanz/filesystem-mcp@latest --port 3000 /path/to/project

Client Configuration

👁 Install in VS Code

Add to .vscode/mcp.json:

{
 "servers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Or install via CLI:

code --add-mcp '{"name":"filesystem","command":"npx","args":["-y","@j0hanz/filesystem-mcp@latest"]}'

👁 Install in VS Code Insiders

Add to .vscode/mcp.json:

{
 "servers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Or install via CLI:

code-insiders --add-mcp '{"name":"filesystem","command":"npx","args":["-y","@j0hanz/filesystem-mcp@latest"]}'

👁 Install in Cursor

Add to ~/.cursor/mcp.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

👁 Install in Visual Studio

Add to <SOLUTIONDIR>.mcp.json or %USERPROFILE%\.mcp.json:

{
 "servers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to ~/.config/goose/config.yaml:

extensions:
 filesystem:
 name: Filesystem MCP
 cmd: npx
 args:
 - -y
 - '@j0hanz/filesystem-mcp@latest'
 enabled: true
 type: stdio

👁 Add to LM Studio

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to claude_desktop_config.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

claude mcp add filesystem-mcp -- npx -y @j0hanz/filesystem-mcp@latest

Or add a project-scoped .mcp.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to ~/.codeium/windsurf/mcp_config.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

amp mcp add filesystem-mcp -- npx -y @j0hanz/filesystem-mcp@latest

Or add to settings.json:

{
 "amp.mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to cline_mcp_settings.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

codex mcp add filesystem -- npx -y @j0hanz/filesystem-mcp@latest

Or add to ~/.codex/config.toml (or .codex/config.toml in a trusted project):

[mcp_servers.filesystem]
command = "npx"
args = ["-y", "@j0hanz/filesystem-mcp@latest"]

Add this JSON in your repository's GitHub Copilot coding agent MCP configuration:

{
 "mcpServers": {
 "filesystem": {
 "type": "local",
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"],
 "tools": ["*"]
 }
 }
}

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to .kiro/settings/mcp.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to ~/.gemini/settings.json:

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

Add to ~/.config/zed/settings.json:

{
 "context_servers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"],
 "env": {}
 }
 }
}

Add to VS Code settings.json under augment.advanced:

{
 "augment.advanced": {
 "mcpServers": [
 {
 "id": "filesystem",
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 ]
 }
}

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

{
 "mcpServers": {
 "filesystem": {
 "command": "npx",
 "args": ["-y", "@j0hanz/filesystem-mcp@latest"]
 }
 }
}

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Use Cases

Explore and Understand a Codebase

Discover project structure and navigate unfamiliar repositories. Start with roots to see allowed directories, use tree for an overview, find to locate files by pattern, and read or read_many to inspect contents.

Relevant tools: roots, ls, find, tree, read, read_many, stat

Search Across Files

Locate specific code patterns, function definitions, or configuration values across a project. Use grep for content search with regex support and find for file name matching.

Relevant tools: grep, find

Edit and Refactor Code

Make precise, targeted edits to source files. Use edit for surgical replacements with dry-run preview, or search_and_replace for bulk changes across multiple files matching a glob pattern.

Relevant tools: edit, search_and_replace, write

Diff and Patch Workflow

Compare file versions and apply patches. Generate a unified diff with diff_files, preview with apply_patch(dryRun: true), then apply. Supports both single-file and multi-file patches (best-effort per file with per-file results[]).

Relevant tools: diff_files, apply_patch

File Management

Create directories, move/rename files, delete files, and verify file integrity via SHA-256 hashing.

Relevant tools: mkdir, mv, rm, calculate_hash, write

Architecture

[MCP Client]
 |
 | Transport: stdio (default) or Node Streamable HTTP (--port)
 v
[MCP Server: filesystem-mcp]
 | Entry: src/index.ts -> src/server/bootstrap.ts
 |
 +-- initialize / initialized
 |
 +-- tools/call ──────────────────────────────────────────
 | +-- [roots] — List allowed workspace roots
 | +-- [ls] — List directory contents
 | +-- [find] — Find files by glob
 | +-- [tree] — Render directory tree
 | +-- [read] — Read file contents
 | +-- [read_many] — Read multiple files
 | +-- [stat] — Get file metadata
 | +-- [stat_many] — Get multiple file metadata
 | +-- [grep] — Search file contents
 | +-- [mkdir] — Create directory
 | +-- [write] — Write file
 | +-- [edit] — Edit file (string replacements)
 | +-- [mv] — Move/rename file
 | +-- [rm] — Delete file
 | +-- [calculate_hash] — SHA-256 hash
 | +-- [diff_files] — Unified diff
 | +-- [apply_patch] — Apply unified patch
 | +-- [search_and_replace]— Bulk search & replace
 |
 +-- resources/read ──────────────────────────────────────
 | +-- internal://instructions
 | +-- internal://tool-catalog
 | +-- internal://workflows
 | +-- internal://tool-info/{name}
 | +-- filesystem-mcp://result/{id}
 | +-- filesystem-mcp://metrics
 |
 +-- prompts/get ─────────────────────────────────────────
 | +-- get-help (optional topic argument)
 | +-- compare-files (original, modified)
 | +-- analyze-path (path)
 | +-- get-tool-help (name)
 |
 +-- Capabilities: logging, resources, tools, prompts, completions, tasks

Request Lifecycle

[Client] -- initialize {protocolVersion, capabilities} --> [Server]
[Server] -- {protocolVersion, capabilities, serverInfo} --> [Client]
[Client] -- notifications/initialized --> [Server]
[Client] -- tools/call {name, arguments} --> [Server]
[Server] -- validate(inputSchema) --> [Handler]
[Handler] -- {content: [{type, text}], structuredContent?, isError?} --> [Client]

MCP Surface

Tools

roots · ls · find · tree · read · read_many · stat · stat_many · grep · mkdir · write · edit · mv · rm · calculate_hash · diff_files · apply_patch · search_and_replace

`roots`

List allowed workspace roots. Call first — all other tools are scoped to these directories.

No parameters.

`ls`

List immediate directory contents: name, path, type, size, modified date.

Parameter	Type	Required	Description
`path`	string	no	Base directory (default: root)
`includeHidden`	boolean	no	Include dotfiles. Default: `false`
`includeIgnored`	boolean	no	Include ignored items (node_modules, .git). Default: `false`
`maxDepth`	integer	no	Max recursion depth (1-50) when pattern is provided
`maxEntries`	integer	no	Max entries before truncation. Default: 20000, Max: 20000
`sortBy`	enum	no	`name` \| `size` \| `modified` \| `type`. Default: `name`
`pattern`	string	no	Relative glob filter (e.g. `*/.ts`). Absolute paths and `..` are rejected
`includeSymlinkTargets`	boolean	no	Resolve symlink targets. Default: `false`
`cursor`	string	no	Pagination cursor from a previous response

`find`

Find files by glob pattern. Returns matching files with metadata.

Parameter	Type	Required	Description
`path`	string	no	Base directory (default: root)
`pattern`	string	yes	Relative glob pattern (e.g. `*/.ts`). Absolute paths and `..` are rejected
`maxResults`	integer	no	Max results (1-10000). Default: 100
`includeIgnored`	boolean	no	Include ignored items. Default: `false`
`includeHidden`	boolean	no	Include dotfiles. Default: `false`
`sortBy`	enum	no	`path` \| `name` \| `size` \| `modified`. Default: `path`
`maxDepth`	integer	no	Max directory depth (0-100)
`cursor`	string	no	Pagination cursor

`tree`

Render a directory tree with bounded recursion. Returns ASCII tree + structured JSON.

Parameter	Type	Required	Description
`path`	string	no	Base directory (default: root)
`maxDepth`	integer	no	Depth (0 = root node only). Default: 5, Max: 50
`maxEntries`	integer	no	Max entries. Default: 1000, Max: 20000
`includeHidden`	boolean	no	Include dotfiles. Default: `false`
`includeIgnored`	boolean	no	Include ignored items. Default: `false`
`includeSizes`	boolean	no	Include file sizes in tree entries. Default: `false`

`read`

Read text file contents. Use head/tail to preview first/last N lines of large files.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file
`head`	integer	no	Read first N lines (1-100000)
`tail`	integer	no	Read last N lines (1-100000)
`startLine`	integer	no	Start line (1-based, inclusive)
`endLine`	integer	no	End line (1-based, inclusive). Requires `startLine`
`includeHash`	boolean	no	Include SHA-256 hash of full file content. Default: `false`

`read_many`

Read multiple text files in one request.

Parameter	Type	Required	Description
`paths`	string[]	yes	Files to read (1-100 paths)
`head`	integer	no	Read first N lines of each file
`tail`	integer	no	Read last N lines of each file
`startLine`	integer	no	Start line (1-based) per file
`endLine`	integer	no	End line (1-based) per file

`stat`

Get file/directory metadata: size, modified, permissions, mime, tokenEstimate.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file or directory

`stat_many`

Get metadata for multiple files/directories in one request.

Parameter	Type	Required	Description
`paths`	string[]	yes	File/directory paths (1-100)

`grep`

Search file contents (grep-like). Returns matching lines with optional context.

Parameter	Type	Required	Description
`path`	string	no	Base directory (default: root)
`pattern`	string	yes	Search text or RE2 regex when `isRegex=true`
`isRegex`	boolean	no	Treat pattern as RE2 regex. Default: `false`
`caseSensitive`	boolean	no	Case-sensitive matching. Default: `false`
`wholeWord`	boolean	no	Match whole words only. Default: `false`
`contextLines`	integer	no	Lines of context before/after (0-50). Default: 0
`maxResults`	integer	no	Max match rows (0-10000). Default: 500
`filePattern`	string	no	Relative glob for candidate files (e.g. `*/.ts`). Default: `*/`
`includeHidden`	boolean	no	Include dotfiles. Default: `false`
`includeIgnored`	boolean	no	Include ignored items. Default: `false`

`mkdir`

Create a new directory (recursive). Idempotent.

Parameter	Type	Required	Description
`path`	string	no	Absolute path to directory to create
`paths`	string[]	no	Multiple directories to create. Either `path` or `paths` required

`write`

Write content to a file, overwriting all existing content. Creates parent directories if needed.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file
`content`	string	yes	Content to write

`edit`

Apply sequential literal string replacements (first occurrence per edit). Use dryRun to preview.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file
`edits`	array	yes	List of non-empty `{oldText, newText}` replacements
`dryRun`	boolean	no	Preview edits without writing. Default: `false`
`ignoreWhitespace`	boolean	no	Treat whitespace sequences as equivalent. Default: `false`

`mv`

Move or rename a file or directory.

Parameter	Type	Required	Description
`source`	string	no	Single path to move (deprecated: use `sources`)
`sources`	string[]	no	Paths to move. Either `source` or `sources` required
`destination`	string	yes	Destination path

`rm`

Permanently delete a file or directory. Irreversible.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file or directory
`recursive`	boolean	no	Delete non-empty directories. Default: `false`
`ignoreIfNotExists`	boolean	no	No error if missing. Default: `false`

`calculate_hash`

Calculate SHA-256 hash of a file or directory.

Parameter	Type	Required	Description
`path`	string	yes	Absolute path to file or directory

`diff_files`

Generate a unified diff between two files. Output feeds directly into apply_patch.

Parameter	Type	Required	Description
`original`	string	yes	Path to original file
`modified`	string	yes	Path to modified file
`context`	integer	no	Lines of context in diff output
`ignoreWhitespace`	boolean	no	Ignore leading/trailing whitespace. Default: `false`
`stripTrailingCr`	boolean	no	Strip trailing carriage returns. Default: `false`

`apply_patch`

Apply a unified diff patch to one or more files. Single-file: throws on failure. Multi-file: best-effort per file with results[]. Workflow: diff_files -> apply_patch(dryRun) -> apply_patch.

Parameter	Type	Required	Description
`path`	string	yes	Path to file (single) or base directory (multi-file patch)
`patch`	string	yes	Unified diff with `@@` hunk headers (single or multi-file)
`fuzzFactor`	integer	no	Max fuzzy mismatches per hunk (0-20)
`autoConvertLineEndings`	boolean	no	Auto-convert line endings. Default: `true`
`dryRun`	boolean	no	Validate without writing. Default: `false`

`search_and_replace`

Bulk search-and-replace across files matching a glob. Replaces all occurrences per file. Always dryRun: true first.

Parameter	Type	Required	Description
`path`	string	no	Base directory (default: root)
`filePattern`	string	no	Relative glob pattern (e.g. `*/.ts`). Default: `*/`
`searchPattern`	string	yes	Text to search. RE2 regex when `isRegex=true`
`replacement`	string	yes	Replacement text. Supports `$1`, `$2` with regex
`isRegex`	boolean	no	Treat as RE2 regex. Default: `false`
`dryRun`	boolean	no	Preview matches with diff. Default: `false`
`includeHidden`	boolean	no	Include dotfiles. Default: `false`
`includeIgnored`	boolean	no	Include ignored items. Default: `false`
`returnDiff`	boolean	no	Return diff even when not dry-run. Default: `false`
`maxFiles`	integer	no	Max files to process before stopping (1-10000)
`caseSensitive`	boolean	no	Case-sensitive matching. Default: `true`

Resources

Resource	URI	MIME Type	Description
Instructions	`internal://instructions`	text/markdown	Comprehensive usage rules and guidelines
Tool Catalog	`internal://tool-catalog`	text/markdown	Tool selection guide and data flow map
Workflows	`internal://workflows`	text/markdown	Standard operating procedures for exploration, search, edit, patch
Tool Info	`internal://tool-info/{name}`	text/markdown	Per-tool contract details, nuances, gotchas
Result Cache	`filesystem-mcp://result/{id}`	text/plain	Ephemeral cached tool output (large results externalized here)
Metrics	`filesystem-mcp://metrics`	application/json	Live per-tool call/error/avgDurationMs snapshot

Prompts

Prompt	Arguments	Description
`get-help`	`topic` (optional)	Return usage instructions. Optionally filter by section heading prefix
`compare-files`	`original`, `modified`	Generate a workflow for comparing two files using `diff_files`
`analyze-path`	`path`	Generate a workflow for analyzing a file or directory
`get-tool-help`	`name`	Return a prompt with the authoritative contract for a specific tool

MCP Capabilities

Capability	Status	Evidence
`logging`	confirmed	`src/server/bootstrap.ts` — registered in capabilities
`resources`	confirmed	`src/server/bootstrap.ts` — 6 resources registered
`tools`	confirmed	`src/server/bootstrap.ts` — 18 tools registered
`prompts`	confirmed	`src/server/bootstrap.ts` — 4 prompts registered
`completions`	confirmed	`src/completions.ts` — path, topic, and tool-name auto-completion
`tasks`	confirmed	`src/server/bootstrap.ts` — optional task support (list, cancel, requests)

Tool Annotations

Annotation	Tools	Value
`readOnlyHint: true`	`roots`, `ls`, `find`, `tree`, `read`, `read_many`, `stat`, `stat_many`, `grep`, `calculate_hash`, `diff_files`	Read-only, idempotent, non-destructive
`destructiveHint: true`	`write`, `edit`, `rm`, `mv`, `search_and_replace`, `apply_patch`	Destructive writes, not idempotent
`idempotentHint: true`	`mkdir`	Idempotent write, non-destructive

Structured Output

All 18 tools define outputSchema (Zod -> JSON Schema) and return structuredContent alongside text content. Set FS_CONTEXT_STRIP_STRUCTURED=true to strip output schemas from tool definitions (reduces token usage for LLMs that don't use structured output).

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Configuration

HTTP & Auth

Variable	Default	Description
`FILESYSTEM_MCP_API_KEY`	(none)	Bearer token required when binding HTTP to a non-loopback host
`FILESYSTEM_MCP_MAX_HTTP_SESSIONS`	`100`	Max concurrent HTTP sessions (1-10,000)
`FILESYSTEM_MCP_HTTP_HOST`	`127.0.0.1`	HTTP server bind address
`FS_CONTEXT_MAX_REQUEST_BYTES`	`4194304` (4 MB)	Max HTTP request body size (1 KB - 256 MB)

File Size Limits

Variable	Default	Description
`MAX_FILE_SIZE`	`10485760` (10 MB)	Max file size for text read operations (1 MB - 100 MB)
`MAX_SEARCH_SIZE`	`1048576` (1 MB)	Max file size for content search/grep (100 KB - 10 MB)
`MAX_READ_MANY_TOTAL_SIZE`	`524288` (512 KB)	Max cumulative size for `read_many` requests (10 KB - 100 MB)
`DEFAULT_SEARCH_TIMEOUT`	`5000`	Search operation timeout in ms (100 - 60,000)

Access Control

Variable	Default	Description
`FS_CONTEXT_ALLOW_SENSITIVE`	`false`	Allow reading sensitive files (.env, .key, credentials, tokens)
`FS_CONTEXT_DENYLIST`	(none)	CSV/newline-separated glob patterns to block (in addition to built-in denylist)
`FS_CONTEXT_ALLOWLIST`	(none)	CSV/newline-separated glob patterns to permit (overrides denylist)

Output & Inline Limits

Variable	Default	Description
`FS_CONTEXT_MAX_INLINE_CHARS`	`20000`	Max inline result chars before externalizing to `filesystem-mcp://result/{id}`
`FS_CONTEXT_MAX_INLINE_MATCHES`	`50`	Max inline search matches before truncation
`FS_CONTEXT_STRIP_STRUCTURED`	`false`	Strip `outputSchema` from tool definitions (reduces tokens)

Tasks

Variable	Default	Description
`FILESYSTEM_MCP_MAX_TASK_TTL_MS`	`3600000` (1 hr)	Max task TTL before auto-eviction (1 s - 24 hr)
`FILESYSTEM_MCP_MAX_CONCURRENT_TASKS`	`100`	Max simultaneous task executions (1-10,000)

Logging & Diagnostics

Variable	Default	Description
`FILESYSTEM_MCP_LOG_LEVEL`	`info`	MCP log level: debug, info, notice, warning, error, critical, alert, emergency
`FS_CONTEXT_DIAGNOSTICS`	`false`	Enable diagnostic logging
`FS_CONTEXT_DIAGNOSTICS_DETAIL`	`false`	Enable detailed diagnostic output
`FS_CONTEXT_TOOL_LOG_ERRORS`	`false`	Log tool errors to stderr
`FS_CONTEXT_SEARCH_WORKERS_DEBUG`	`false`	Debug logging for search worker pool

Performance

Variable	Default	Description
`FS_CONTEXT_SEARCH_WORKERS`	CPU cores (≤ 8)	Concurrent search worker threads (1-16)
`FS_CONTEXT_LIST_CURSOR_TTL_MS`	`300000` (5 min)	Cursor TTL for `ls` pagination snapshots

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HTTP Endpoints

When started with --port <number>, the server exposes a single MCP endpoint:

Method	Path	Purpose
`POST`	`/mcp`	Initialize session or send requests (Streamable HTTP)
`GET`	`/mcp`	HTTP streaming session endpoint
`DELETE`	`/mcp`	Terminate a session

Required headers:

mcp-protocol-version — use the negotiated MCP protocol version on post-initialize HTTP requests
mcp-session-id — required for GET/DELETE (returned by POST on initialize)

Authentication: Requests to non-loopback HTTP binds require FILESYSTEM_MCP_API_KEY; clients must then send Authorization: Bearer <key>. Loopback-only binds may omit auth for local use. Uses SHA-256 timing-safe comparison.

CORS: Only localhost origins allowed (127.0.0.1, ::1, localhost).

Host validation: Loopback HTTP binds validate the Host header (localhost, 127.0.0.1, [::1]) to reduce DNS rebinding risk. Non-loopback binds still require FILESYSTEM_MCP_API_KEY.

Security

Control	Status	Evidence
Path sandboxing	confirmed	`src/lib/paths.ts` — all paths validated against allowed roots
Traversal prevention	confirmed	`src/lib/paths.ts` — resolved paths checked after normalization
Symlink escape prevention	confirmed	`src/__tests__/security.test.ts` — symlink boundary enforcement
Sensitive file denylist	confirmed	`src/lib/constants.ts` — blocks `.git`, `.env*`, SSH keys, certs, secrets
Origin validation	confirmed	`src/server/bootstrap.ts` — localhost-only Origin allowlist
Bearer auth	confirmed	`src/server/bootstrap.ts` — optional `FILESYSTEM_MCP_API_KEY` with timing-safe compare
Input validation	confirmed	`src/schemas.ts` — Zod strict schemas on all tool inputs
Request body limit	confirmed	`src/server/bootstrap.ts` — configurable max request size (413 on overflow)
Remote bind guard	confirmed	`src/server/bootstrap.ts` — refuses non-loopback bind without `FILESYSTEM_MCP_API_KEY`

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Development

dev — tsc --watch --preserveWatchOutput — Watch mode TypeScript compilation
dev:run — node --env-file=.env --watch dist/index.js — Run server with auto-reload
start — node dist/index.js — Run production server
build — node scripts/tasks.mjs build — Clean build
test — node scripts/tasks.mjs test — Build + run all tests
test:fast — node --test --import tsx/esm src/__tests__/**/*.test.ts node-tests/**/*.test.ts — Run tests without build
lint — eslint . — Lint source
type-check — node scripts/tasks.mjs type-check — Type-check src + tests
format — prettier --write . — Format code
inspector — npm run build && npx -y @modelcontextprotocol/inspector node dist/index.js ${workspaceFolder} — Launch MCP Inspector

Build and Release

CI: .github/workflows/release.yml — runs lint, type-check, test, build before tagging/publishing.
Docker: Multi-stage build with node:24-alpine. Builder compiles TypeScript + native modules (re2); release stage runs as non-root mcp user.
npm: npm run prepublishOnly runs lint + type-check + build.

Troubleshooting

"No allowed directories" — Pass at least one directory argument or use --allow-cwd.
Sensitive file blocked — Files matching the denylist (.env*, .git, SSH keys) are blocked by design. Check src/lib/constants.ts for the full list.
Large result externalized — When tool output exceeds inline limits, it's cached as a resource at filesystem-mcp://result/{id}. Read the resource URI to get the full content.
Stdio: logs on stdout — Keep logs on stderr only. The server uses console.error for diagnostics.
HTTP 413 — Request body exceeds FS_CONTEXT_MAX_REQUEST_BYTES. Increase the limit or reduce payload size.
HTTP 401 — FILESYSTEM_MCP_API_KEY is set but the request is missing or has an incorrect Authorization: Bearer header.

Credits

Dependency	Description
@modelcontextprotocol/server	MCP server SDK package
@modelcontextprotocol/client	MCP client SDK package
@modelcontextprotocol/node	Node transport package for MCP runtime
commander	CLI argument parsing
diff	Unified diff generation and patch application
ignore	`.gitignore` pattern matching
re2	Safe RE2 regex engine (no ReDoS)
zod	Schema validation and JSON Schema generation

License

MIT License. See LICENSE for details.

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This server cannot be installed

license - permissive license

quality - not tested

maintenance

How are these scores calculated?

Maintenance

–Maintainers

2dResponse time

1dRelease cycle

56Releases (12mo)

Commit activity

Issues opened vs closed

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⇱ FS Context MCP Server by j0hanz | Glama

Filesystem MCP Server

Table of Contents

Overview

Key Features

Requirements

Quick Start

Docker

CLI Usage

Client Configuration

Use Cases

Explore and Understand a Codebase

Search Across Files

Edit and Refactor Code

Diff and Patch Workflow

File Management

Architecture

Request Lifecycle

MCP Surface

Tools

roots

ls

find

tree

read

read_many

stat

stat_many

grep

mkdir

write

edit

mv

rm

calculate_hash

diff_files

apply_patch

search_and_replace

Resources

Prompts

MCP Capabilities

Tool Annotations

Structured Output

Configuration

HTTP & Auth

File Size Limits

Access Control

Output & Inline Limits

Tasks

Logging & Diagnostics

Performance

HTTP Endpoints

Security

Development

Build and Release

Troubleshooting

Credits

License

Maintenance

Resources

Appeared in Searches

Latest Blog Posts

MCP directory API

`roots`

`ls`

`find`

`tree`

`read`

`read_many`

`stat`

`stat_many`

`grep`

`mkdir`

`write`

`edit`

`mv`

`rm`

`calculate_hash`

`diff_files`

`apply_patch`

`search_and_replace`