Strong tool naming (verb_noun pattern), comprehensive descriptions (avg 150 chars, well above 10-char minimum), and complete input schemas with type definitions and constraints. All 7 tools have clear, actionable descriptions that guide LLM selection. Parameters include proper constraints (minLength, minimum, maximum, pattern, enum-like descriptions). Output schemas are documented in code but not exposed in tool definitions. Error handling is present in client layer but not surfaced to LLM. No tool annotations (readOnlyHint, destructiveHint). Composition is clean, each tool has one responsibility. Naming is consistent and verb-driven. Minor gaps: output schemas not formally declared in tool registration, no per-tool error recovery guidance.

• Add formal output schema documentation to each tool definition. Example: 'Returns: {plans: [{id, country, price_usd, data_gb, days, group_id}], total_count: number}'. This enables LLMs to plan downstream calls.
• Declare readOnlyHint: true on all 7 tools in tool registration. This signals to agents that results are cacheable and retries are safe.
• Enhance error descriptions with recovery guidance. E.g., 'Country not found. Try search_destinations() with a partial name like "jap" for Japan.'
• Document pagination limits in list_plans and list_popular_destinations descriptions. State: 'Returns up to 20 plans by default. Use limit parameter (1-50) to adjust.'
• Add prerequisite clarity to list_my_esims and get_esim_usage: 'Requires CHEAPERESIM_API_TOKEN environment variable. If missing, these tools will not be available.'