Filesystem

Read, write, and navigate files inside the MCP runner's sandbox — no credentials needed.

Requires Growth plan or above.

Enable Filesystem

Stateless — no credentials required. Toggle Filesystem on at /dashboard/connections. All file operations are scoped to a per-app sandbox directory.

Example

Write a generated report to disk so a later step can read it back.

app/api/save-report/route.ts

export async function POST() {
  const res = await fetch('https://leash.build/api/integrations/filesystem/write_file', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.LEASH_API_KEY!,
      'content-type': 'application/json',
    },
    body: JSON.stringify({
      path: '/workspace/report.md',
      content: '# Weekly report\n\nRevenue is up 12% WoW.\n',
    }),
  })
  const { data } = await res.json()

  // data =>
  // {
  //   path: '/workspace/report.md',
  //   bytesWritten: 41,
  //   created: true
  // }

  return Response.json(data)
}

Available tools

read_text_file / read_file / read_media_file / read_multiple_files — read content.
write_file / edit_file — write or in-place edit.
create_directory / move_file — directory + path management.
list_directory / list_directory_with_sizes / directory_tree — directory listings.
search_files — recursive glob/regex search.
get_file_info — file metadata.
list_allowed_directories — directories the sandbox exposes.

Common gotchas

Paths are sandboxed. Operations outside the directories returned by list_allowed_directories are rejected with EACCES.
Storage is ephemeral. Files survive the lifetime of the MCP runner instance; treat the FS as scratch space, not durable storage.
read_media_file returns base64. Decode before re-uploading or serving as binary.

See the Filesystem MCP server source for the underlying provider docs.

Other languages: see SDK overview.