Single tool with minimal definition quality. Tool name 'generate_candidate_patches' is verb-noun compliant but generic. Input schema present with basic types (string, integer) but lacks parameter descriptions entirely, critical violation of pattern:tool-description. No output schema documented. Tool description (11 words, ~80 chars) is below the 10 - 1024 char baseline and provides no context on WHEN to use, WHAT it returns, or prerequisites. No error handling guidance. No input validation or constraints (e.g., line number bounds, code length limits). Parameters lack descriptions, making it impossible for LLMs to understand what 'source_code' and 'faulty_line' represent or how to construct valid calls.

• Add descriptions to all input parameters. Example: 'source_code (string): Valid Python source code as a single string. Multi-line code should use \n line separators.' and 'faulty_line (integer): 1-indexed line number containing the fault. Must be >= 1 and <= total lines in source_code.'
• Expand tool description to 100 - 200 chars explaining purpose, when to use, and what it returns. Example: 'Generate candidate bug-fix patches by applying AST mutation operators (off-by-one boundary fixes, operator inversions) to a specified faulty line. Returns a list of patched code variants with mutation type and validity status. Use this to explore repair candidates before validation.'
• Document output schema in the tool definition. Declare that the response is an array of objects with fields: operator (string, enum: 'off_by_one'|'invert_binop'), faulty_line (integer), patched_code (string), status (string, enum: 'VALID_AST'|'PARSE_ERROR').
• Add input validation with actionable error messages. Return structured errors like '{"error": "Invalid faulty_line: 0. Must be >= 1 and <= 6 (total lines in source_code)."}' instead of silently skipping failures.
• Declare parameter constraints in descriptions. Specify that source_code must be valid Python, faulty_line must be a positive integer within the code's line range, and document the mutation operators applied (off-by-one, operator inversion).