## Motivation and Context
The MCP specification defines `notifications/progress` for reporting incremental progress
during long-running tool operations. The Ruby SDK did not yet support this, so tools had no way to
send progress updates to clients. This caused the `tools-call-with-progress` conformance test to fail.
This adds an `MCP::ServerContext` wrapper that provides a `report_progress` method on
`server_context`. Tools call `server_context.report_progress(value, total:, message:)` to send
notifications back to the client. The method is a no-op when no `progressToken` was provided,
so tools can call it unconditionally without checking for a token.
This design is consistent with the TypeScript and Python SDKs, which provide progress
reporting through a context object rather than a separate parameter.
On the client side, `Client#call_tool` now accepts a `progress_token:` parameter that sets
`_meta.progressToken` in the request.
Ref: https://modelcontextprotocol.io/specification/latest/server/utilities/progress
## How Has This Been Tested?
Added comprehensive tests in `test/mcp/server_progress_test.rb` covering `notify_progress`,
tool integration with progress, block-defined tools, `**kwargs` tools, and no-op behavior
without a token.
Added client tests for `progress_token:` parameter inclusion and omission.
Added `test/mcp/server_context_test.rb` test for non-Hash `server_context` preservation
when `_meta` is present.
Conformance: `tools-call-with-progress` removed from expected failures.
## Breaking Change
`server_context` is now always an `MCP::ServerContext` instance when passed to tools,
even if the server has no context configured. Code that checks `server_context ?` to
detect a nil context will need to be updated, as `ServerContext` is always truthy.
`ServerContext` delegates method calls to the underlying context object via
`method_missing`, so `server_context[:key]` and other accessor patterns continue to work.
In practice, this is unlikely to affect users. A tool that declares `server_context:`
is opting in to use the context; if the server has no context configured, that is a
server configuration issue rather than something the tool should handle with a nil check.
This PR moves `MCP::Annotations` from lib/mcp.rb to lib/mcp/annotations.rb for better organization,
following the pattern used for other classes such as `Tool::Annotations`.
This PR also adds the missing `last_modified` attribute to `MCP::Annotations`:
https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/schema/2025-11-25/schema.ts#L1701-L1736
It also adds a `to_h` method for serialization and includes comprehensive test coverage.
NOTE: This code is unused within the ruby-sdk repository, but it is kept for compatibility, as it may be used by users.
This commit implements optional JSON Schema validation for tool outputs according to the MCP specification:
- Add MCP::Tool::OutputSchema class mirroring InputSchema functionality
- Support output_schema in class definitions, Tool.define, and OutputSchema objects
- Include validate_result method for runtime validation
- Update MCP::Client::Tool to track output schemas
- Add comprehensive test coverage with 249 passing tests
- Update README with dedicated Tool Output Schemas section
- Follow MCP spec requirements for server/client validation
Follow-up to #27.
This PR fixes the following build error:
```console
$ bundle exec rake
/Users/koic/.rbenv/versions/3.5-dev/lib/ruby/3.5.0+1/bundled_gems.rb:59:in 'Kernel.require': cannot load such file -- mcp/transports/stdio (LoadError)
Did you mean? mcp/transports/stdio_transport_test
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/3.5.0+1/bundled_gems.rb:59:in 'block (2 levels) in Kernel#replace_require'
from /Users/koic/src/github.com/modelcontextprotocol/ruby-sdk/test/mcp/transports/stdio_transport_test.rb:4:in '<top (required)>'
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/3.5.0+1/bundled_gems.rb:59:in 'Kernel.require'
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/3.5.0+1/bundled_gems.rb:59:in 'block (2 levels) in Kernel#replace_require'
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/gems/3.5.0+1/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:21:in 'block in <main>'
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/gems/3.5.0+1/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:6:in 'Array#select'
from /Users/koic/.rbenv/versions/3.5-dev/lib/ruby/gems/3.5.0+1/gems/rake-13.3.0/lib/rake/rake_test_loader.rb:6:in '<main>'
rake aborted!
Command failed with status (1)
/Users/koic/.rbenv/versions/3.5-dev/bin/bundle:25:in 'Kernel#load'
/Users/koic/.rbenv/versions/3.5-dev/bin/bundle:25:in '<main>'
Tasks: TOP => default => test
(See full trace by running task with --trace)
```
https://github.com/modelcontextprotocol/ruby-sdk/actions/runs/15428236624/job/43420346011
The following is stated in #27.
> Breaking Changes
> `MCP::Transports::StdioTransport` is now `MCP::Server::Transports::StdioTransport`
What is shown here is the new name `MCP::Server::Transports::StdioTransport`, not `MCP::Server::Transports::Stdio`.
Therefore, the file path has been updated from `lib/mcp/server/transports/stdio.rb` to `lib/mcp/server/transports/stdio_transport.rb` to
match the module name. If `MCP::Server::Transports::Stdio` is preferred instead, please let me know and I will open a separate PR.
