Four tools with clear, concise descriptions (avg 95 chars) and complete input schemas. All parameters are typed and described. However, output schemas are undocumented, LLMs cannot predict response structure for planning. Error handling returns structured objects with 'error' fields but lacks recovery guidance. Tool names are verb-noun (read, validate, diff, missing) and unambiguous. No tool annotations (readOnlyHint, etc.). Composition is sound: each tool has one responsibility. Security is adequate for read-only operations, but no explicit permission gates or audit logging.

• Document output schemas for all tools. Example for 'read': {"path": string, "vars": {[key]: string}, "count": int, "error": string|null}. This enables LLMs to extract fields and plan chained calls.
• Add recovery guidance to error responses. When FileNotFoundError occurs, return: 'error: File not found at <path>. Verify the path exists and is readable, or use a relative path from the project root.'
• Add tool annotations to the FastMCP decorator. Mark all four tools with readOnlyHint=true and idempotentHint=true so clients know they are safe to retry and do not modify state.
• Enhance parameter descriptions with format constraints. Change 'Path to the .env file' to 'Absolute or relative path to a .env file (e.g., .env, config/.env.local). Must be readable.'
• Add a 'limit' parameter to 'read' with a default of 1000 and document: 'Maximum number of variables to return. If the file contains more, only the first <limit> are returned. Use validate() to check for missing vars.'