Six tools with basic schemas and descriptions, but significant gaps in parameter documentation and output schema clarity. Tool names lack action verbs (add, calculate, check_payment_history are acceptable but onetime_add, subscription_add, metered_add are vague about what distinguishes them). All tools have descriptions (10-80 chars), but most are too brief to guide LLM selection. Input schemas present but parameter descriptions are minimal (1-2 words). No documented output schemas. Error handling and recovery guidance absent. Composition issues: three tools (onetime_add, subscription_add, metered_add) perform the same operation (add two numbers) with different payment models, this should be a single tool with a payment_mode parameter, not three separate tools.

• Consolidate onetime_add, subscription_add, metered_add into a single 'add' tool with a payment_mode enum parameter (values: free, onetime, subscription, metered). This eliminates duplication and lets the LLM choose the payment model as part of a single call.
• Expand tool descriptions to 100-200 chars. Include: what the tool does, when to use it (vs similar tools), prerequisites (e.g., 'Requires logged-in user'), and what it returns. Example: 'Adds two numbers together. Use this for simple arithmetic. Requires active subscription. Returns {result: number, calculation_id: string}'.
• Document output schemas for all tools. Add a 'Returns' section to each tool definition showing the structure of the response (e.g., {result: number, timestamp: string}).
• Add min/max constraints to numeric parameters. Example: 'a (number, -1e6 to 1e6): First operand. Supports integers and decimals.'
• Add error handling guidance. Example: 'If division by zero, returns error code DIVIDE_BY_ZERO with message "Cannot divide by zero. Use a non-zero divisor."' This helps LLMs recover from failures.