fix: add missing size field to ResourceSchema#1574
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Adds the optional `size` field to `ResourceSchema` to match the MCP specification. The auto-generated spec types already include `size?: number` on the Resource interface, but the hand-maintained Zod schema was missing it. Rebased onto main after schemas moved from types.ts to schemas.ts.
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## Motivation and Context The MCP specification defines an optional `size` field on the `Resource` type, added in spec revision 2025-06-18 and retained in 2025-11-25: https://modelcontextprotocol.io/specification/2025-11-25/server/resources > The size of the raw resource content, in bytes (i.e., before base64 > encoding or any tokenization), if known. This can be used by Hosts to > display file sizes and estimate context window usage. `MCP::Resource` was missing this field, so servers had no way to declare a resource's byte size. Without it, hosts cannot show file sizes or estimate context window usage before reading the resource contents. This aligns the Ruby SDK with the spec, matching the TypeScript SDK (modelcontextprotocol/typescript-sdk#1574). ## How Has This Been Tested? Added tests in `test/mcp/resource_test.rb`: - `#to_h` omits `size` when nil - `#to_h` includes `size` when present The full unit suite and RuboCop pass locally. ## Breaking Changes None. `size:` is a new optional keyword argument defaulting to `nil`, and it is omitted from `#to_h` output when not set, so existing callers are unaffected.
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## Motivation and Context The MCP specification defines an optional `size` field on the `Resource` type, added in spec revision 2025-06-18 and retained in 2025-11-25: https://modelcontextprotocol.io/specification/2025-11-25/server/resources > The size of the raw resource content, in bytes (i.e., before base64 > encoding or any tokenization), if known. This can be used by Hosts to > display file sizes and estimate context window usage. `MCP::Resource` was missing this field, so servers had no way to declare a resource's byte size. Without it, hosts cannot show file sizes or estimate context window usage before reading the resource contents. This aligns the Ruby SDK with the spec, matching the TypeScript SDK (modelcontextprotocol/typescript-sdk#1574). ## How Has This Been Tested? Added tests in `test/mcp/resource_test.rb`: - `#to_h` omits `size` when nil - `#to_h` includes `size` when present - `#to_h` includes `size` when zero (distinguishes an unset size from a 0-byte resource) The full unit suite and RuboCop pass locally. ## Breaking Changes None. `size:` is a new optional keyword argument defaulting to `nil`, and it is omitted from `#to_h` output when not set, so existing callers are unaffected.
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Summary
sizenumber field toResourceSchemain the Zod schema definition, matching the MCP specification (added in spec revision 2025-06-18)spec.types.ts(auto-generated from spec) already includessize?: numberon theResourceinterface, but the hand-maintained Zod schema was missing itResourceLinkSchema,ListResourcesResultSchema) inherit the field automaticallyFixes #1573
Test plan
pnpm typecheck:allpassespnpm --filter @modelcontextprotocol/core test— all 440 tests passResourceSchema.shape.sizeexists after the change🤖 Generated with Claude Code