Two tools with basic schemas and descriptions, but significant gaps in parameter documentation and error guidance. Calculator has a clear, concise description (89 chars) and proper schema with type constraints. Memory_store description is longer (165 chars) but lacks clarity on when to use each action; parameters lack descriptions for 'key' and 'value' fields. Neither tool documents output structure or provides recovery guidance on errors. No tool annotations (readOnlyHint/destructiveHint). Error handling returns plain text rather than structured guidance. Naming is acceptable but generic ('memory_store' lacks verb). Overall: functional but below production baseline of 194 chars avg description and 100% param coverage.

• Add descriptions to memory_store parameters: 'key' → 'The key to store/retrieve (required for set/get/delete; ignored for list)', 'value' → 'The value to store (required only for set action)'.
• Document output schemas in tool definitions. E.g., calculator returns {type: 'object', properties: {result: {type: 'number'}, expression: {type: 'string'}}}. Memory_store returns {type: 'object', properties: {status: {type: 'string'}, keys: {type: 'array'}}} for list action.
• Replace plain-text error strings with structured error objects: {error: 'INVALID_EXPRESSION', message: 'Expression contains disallowed characters. Only 0-9, +, -, *, /, (, ), and . are allowed.', recovery: 'Retry with a valid mathematical expression.'}
• Add tool annotations: calculator with readOnlyHint=true; memory_store 'delete' action with destructiveHint=true; all actions with idempotentHint=true (safe to retry).
• Expand memory_store description to clarify state persistence: 'Store and retrieve key-value pairs in session memory (persists for the lifetime of this server instance). Actions: set (store/overwrite), get (retrieve), list (show all), delete (remove). Note: delete is irreversible.'.