🗃️ 1. MCS Motivation Overview
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📄️ 2. Core Idea
MCS defines a thin glue layer between a Language Model and any existing interface such as REST, GraphQL, CAN-Bus, EDI, or even filesystems.
🗃️ 3. Minimal Driver Contract
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📄️ 4. Orchestrator & ToolDriver
When using multiple MCS drivers in a chain, each driver must autonomously determine if a function call in the LLM response is intended for it, assuming drivers maintain an internal representation of their tools (implemented in varying ways without a strict convention). The LLM's output is passed sequentially through all processllmresponse methods, and the system prompts from all drivers are combined and fed to the LLM. This can lead to side effects, especially with numerous drivers offering different formats. The LLM may struggle to cleanly separate and handle them, resulting in parsing errors or unreliable calls.
📄️ 5. Configuration & Instantiation
Drivers are configured via constructors, e.g., URLs for specs, auth tokens, proxies. Use libraries like Pydantic for validation.
📄️ 6. Optional Capabilities
MCS keeps the base contract tiny. Optional behavior is signaled via capability flags in DriverMeta. Consumers must feature-detect before invoking an optional method (i.e., check if the flag exists in meta.capabilities and then dynamically call the corresponding method).
📄️ 7. Autostart Convention
Autostart is mostly obsolete in MCS, as existing interfaces (e.g., HTTP endpoints) are used directly. For local systems, employ direct code (e.g., mcs-driver-filesystem-localfs) without spinning up extra processes.
📄️ 8. Security, Usability and Integration
A central goal of the Model Context Standard (MCS) is to connect LLMs to external systems directly and minimally. Unlike MCP, MCS avoids a custom protocol, relying on mature technologies like HTTP, OpenAPI, or Docker that are already proven secure. This eliminates many potential attack surfaces typical of new standards.
🗃️ 9 · LLM Prompt Patterns
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📄️ 10. Relation to MCP
MCS does not compete with MCP directly. It generalizes the same idea of standardizing LLM external system connections without imposing a new wire protocol or stack. MCP updates in 2025 (e.g., streamable HTTP transport, OAuth Resource Servers with mandatory Resource Indicators per RFC 8707) have improved its robustness, but vulnerabilities persist. Mostly because of the new protocol stack. MCP uses it and MCS shows that this is not needed.
📄️ 11. Versioning & Compatibility
MCS follows Semantic Versioning (MAJOR.MINOR.PATCH) for the specification document itself, ensuring clear evolution while maintaining backward compatibility where possible.
📄️ 12. Next Steps
Core Standard Enhancements (Define in Spec for Consistency Across SDKs)