SimFuse MCP exposes 2 tools with partial schema coverage. plan-trip has a complete input schema with typed parameters and descriptions (stops array with country/days objects, currency, usage, start date). create-checkout-session lacks any visible input schema in the provided source. Both tools have brief descriptions (plan-trip: 73 chars, create-checkout-session: 56 chars) that meet minimum length but lack actionable context (when to call, what it returns, prerequisites). No output schemas documented. No error handling guidance visible. Tool naming follows verb_noun pattern (plan-trip, create-checkout-session) which is good, but descriptions do not explain dependencies or expected return structure.

• Add complete input schema to create-checkout-session with parameter types, descriptions, and constraints (e.g., items array structure, payment method enum).
• Document output schemas for both tools. Formalize the structuredContent structure (trip, options, recommendation, reason, warnings, planner_url, checkout for plan-trip; session_id, checkout_url, expires_at for create-checkout-session).
• Expand tool descriptions to 100 - 200 chars. Include: (1) what it does, (2) when to call it vs alternatives, (3) key return fields. Example: 'Plan a multi-country trip and get eSIM package recommendations. Call this first to analyze stops and compare coverage options. Returns trip itinerary, recommended packages, and checkout session ID.'
• Add enum constraints to plan-trip 'usage' parameter: usage: {type: 'string', enum: ['light', 'medium', 'heavy'], description: 'Expected data usage level...'}.
• Add error handling guidance in descriptions. E.g., 'If a country is unsupported, the response includes a warning. If all stops lack coverage, returns complete=false in options.'

Inferred effective spec: 2025-06-18+.

• Relies on Stateful initialize / Mcp-Session-Id (removed; protocol is stateless) - make each request self-contained