Add size field to MCP::Resource per MCP specification#1
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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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Practice/self-review PR. Superseded by the upstream PR modelcontextprotocol#393. Closing. |
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Motivation and Context
The MCP specification defines an optional
sizefield on theResourcetype, added in spec revision 2025-06-18 and retained in 2025-11-25:https://modelcontextprotocol.io/specification/2025-11-25/server/resources
MCP::Resourcewas missing this field, so servers had no way to declare a resource's byte size. 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_homitssizewhen nil#to_hincludessizewhen present#to_hincludessizewhen 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 tonil, omitted from#to_hwhen not set.Types of changes
Checklist