Set default content to an empty array instead of nil
#150
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atesgoral
previously approved these changes
Oct 2, 2025
juharris
reviewed
Oct 2, 2025
lib/mcp/tool/response.rb
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| error = deprecated_error | ||
| end | ||
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| @content = content |
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Should we instead handle when nil is passed to this method?
Suggested change
| @content = content || [] |
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Yeah, that makes sense! I've added test code for that case and updated this PR.
Follow-up to modelcontextprotocol#147. According to the specification schema, `content` is not optional and therefore cannot be omitted: ```typescript interface CallToolResult { _meta?: { [key: string]: unknown }; content: ContentBlock[]; isError?: boolean; structuredContent?: { [key: string]: unknown }; [key: string]: unknown; } ``` https://modelcontextprotocol.io/specification/2025-06-18/schema#calltoolresult Instead of `nil`, an empty array is set as the default value. There may be a better value for `content`, but at the very least it should not be missing.
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juharris
approved these changes
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atesgoral
approved these changes
Oct 3, 2025
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Motivation and Context
Follow-up to #147.
According to the specification schema,
contentis not optional and therefore cannot be omitted:https://modelcontextprotocol.io/specification/2025-06-18/schema#calltoolresult
Instead of
nil, an empty array is set as the default value.There may be a better value for
content, but at the very least it should not be missing.How Has This Been Tested?
The related test code has been updated.
Breaking Changes
#147 is unreleased, there are no breaking changes on the main branch.
Types of changes
Checklist