Vault Keeper demonstrates basic tool structure with visible input schemas and descriptions for all 6 tools. However, multiple critical gaps prevent a higher score: (1) descriptions are minimal (10-60 chars, below the 50-200 char baseline for LLM optimization); (2) parameter descriptions exist but lack constraints, ranges, or format guidance; (3) no output schema documentation; (4) error responses are free-text strings without recovery guidance; (5) security issues including hardcoded VAULT_ROOT and no permission checks; (6) no indication of idempotency or mutation semantics beyond informal 'Risk' labels. The tools follow verb_noun naming convention well (get_next_id, create_note, add_backlink), and all input parameters are typed with descriptions, but the descriptions are surface-level. Tools like 'move_note' and 'add_backlink' lack explicit guidance on side effects, error recovery, or validation rules. Per-tool average is 42/100.

• Expand all tool descriptions to 50-200 characters. Example: 'create_note' should read 'Creates a new markdown note file at the specified path within the vault. Each path must be unique; use move_note to rename or relocate existing notes. Useful for initializing new notes with boilerplate content.' (118 chars)
• Document output schema for each tool. Example: 'Returns a JSON object: {"status": "success" | "error", "message": string, "path"?: string, "timestamp"?: ISO8601 string}'
• Add parameter constraints. Example: 'folder_path: Relative path to scan (must exist, alphanumeric + hyphens + underscores only, max 255 chars, no ../ or ./ relative traversal)'
• Provide actionable error messages with recovery steps. Example: 'File already exists at {path}. To overwrite, use move_note to rename the existing file first, or delete it manually.' or 'Parent note not found. Use create_note to initialize {parent_note_rel} first.'
• Add tool annotations (destructiveHint) to mutation tools. Register create_note, prepend_text_to_file, move_note, add_backlink with destructiveHint: true in the MCP tool definition.
• Move VAULT_ROOT to an environment variable or server configuration. Example: vault_root = os.getenv('VAULT_ROOT', os.path.expanduser('~/Documents/Vault')) with validation that it points to an existing directory.
• Implement permission checks or authentication. Add a server-side request context that verifies the caller's identity and role before executing write operations. Return 403 Forbidden if unauthorized.