Travel MCP

Travel MCP is a Riegel Systems engineering case in the field of agentic systems & MCP engineering. The travel use case serves as a concrete demonstrator for the technical requirements of production-ready agentic systems – not as a travel portal.

The core message:

Reliable agentic systems require more than tool calling.

Production-ready agent systems need safety boundaries, provider abstraction, semantic validation, observability and robust failure handling.

Architecture

MCP Tools

Via the Model Context Protocol, the server provides the following tools, among others: search_package_trips, compare_offers, inspect_offer, get_final_prebooking_price, get_search_status and reset_session. The search runs across multiple providers in parallel; a normalized offer model delivers comparable results.

Safety Engineering

The central differentiator is the technical action boundaries:

• No binding booking – the automation consistently stops before the last binding action.
• No payment and no real personal data are transmitted.
• BookingSafetyGuard: Potentially binding actions are actively blocked – based on button texts (“Book now”, “Order with obligation to pay”, “Proceed to payment”, …), URL patterns (/payment, /booking/confirm, …), form actions and HTML classes.
• SafeBrowser: Domain allowlist per provider, SSRF protection (blocking of internal IPs in production), popup and new-tab blocking, blocking of javascript:/data:/file: schemes.
• No CAPTCHA bypass, no stealth or fingerprint evasion.
• Evidence Recorder with limits (screenshots, HTML snapshots, file/session sizes) and path traversal protection.

Production Hardening

Based on the real implementation:

• Circuit Breaker – opens after technical errors, half-open after cooldown, closes after success (non-technical errors such as NO_RESULTS do not affect the breaker).
• Rate Limiting – conservative minimum intervals between requests (e.g. 5 s); exceeded requests are rejected with RATE_LIMIT_EXCEEDED.
• Concurrent Search Control – parallel searches per provider are blocked with PROVIDER_BUSY.
• Selector-drift detection and semantic validation of the extracted results.
• Challenge Detection (captcha/challenge detection), overlay handling and consent/cookie dialog handling.
• Session Cleanup and freshness TTLs for offers, as well as defined price-confirmation levels.

As an internal engineering test, a controlled production canary with 10 live searches was carried out successfully (100% success rate, no selector/semantic drift, no challenges, rate-limiter and circuit-breaker behavior validated). This is an internal load proof of the architecture – not a general product promise.

Capability demonstrated

Travel MCP shows that Riegel Systems can build agentic systems with clear technical action boundaries: MCP server development, multi-provider orchestration, secure browser automation and the scaling of prototypes into production-hardened systems with observability and failure handling.