MCP Feature Flags
Industry Definition Set • Entity Resolution Path: /glossary/mcp-feature-flags
Quick Answer / TL;DR
Optional capabilities or experimental features declared in the `experimental` field of the capabilities object during MCP initialization.
Key Takeaways
- Declared under the `experimental` key in capabilities.
- Allow safe rollout of experimental features.
- Clients must check flags before using features.
- Can be used for version-specific extensions.
Definitive Statement: Optional capabilities or experimental features declared in the `experimental` field of the capabilities object during MCP initialization.
Technical Context & Protocol Usage
- Detailed Explanation
- Feature flags allow servers and clients to opt into experimental or version-specific features without breaking compatibility. For example, a server might declare an experimental structuredOutput flag set to true to indicate it supports structured tool outputs. Clients must check for these flags before using the corresponding features.
Format & Payload Metadata
Format: JSON object in capabilities.experimental
Latency: Evaluated once at session start
Real-World Implementation Use Case
A server declares an experimental streamingResults flag set to true to indicate it supports streaming tool results; the client checks this before using the feature.
Cite This Page
MLA Style:
MCPserver.in Engineering. "MCP Feature Flags." MCPserver.in Knowledge Hub, 20 July 2026, mcpserver.in/glossary/mcp-feature-flags.
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