Allow boolean and enum in registerPrompt argsSchema #691
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This PR introduces types for prompt arguments that are not supported by the MCP protocol specification. The protocol clearly defines prompt arguments as string-only ({ [key: string]: string }). Adding boolean and enum support would require a protocol specification change first, not just an SDK modification. This change would break compatibility with other MCP implementations and violates the protocol contract.
This was referenced Jun 29, 2025
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@ihrpr thank you for the feedback. I opened #710 with enum support only as those are strings. I also opened modelcontextprotocol/modelcontextprotocol#875 in the spec to request boolean support. |
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Motivation and Context
Being able to take user input that is boolean or enumerated values is useful when creating prompt callback functions and allows deeper prompt argument validation than strings only.
How Has This Been Tested?
Unit test coverage added
Breaking Changes
No breaking changes, backwards compatibility is maintained
Types of changes
Checklist
Additional context
Other Zod types, such as number, could be supported as well