ruby-sdk/conformance
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Koichi ITO bbe637612b Support progress notifications per MCP specification
## 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.
2026-03-10 01:49:09 +09:00
..
expected_failures.yml Support progress notifications per MCP specification 2026-03-10 01:49:09 +09:00
README.md Support running MCP conformance tests against the Ruby SDK 2026-03-02 14:50:03 +09:00
runner.rb Support running MCP conformance tests against the Ruby SDK 2026-03-02 14:50:03 +09:00
server.rb Support progress notifications per MCP specification 2026-03-10 01:49:09 +09:00

MCP Conformance Tests

Validates the Ruby SDK's conformance to the MCP specification using @modelcontextprotocol/conformance.

Prerequisites

  • Node.js (for npx)
  • bundle install completed

Running the Tests

Run all scenarios

bundle exec rake conformance

Starts the conformance server, runs all active scenarios against it, prints a pass/fail summary for each scenario, and exits with a non-zero status code if any unexpected failures are detected. Scenarios listed in expected_failures.yml are allowed to fail without affecting the exit code.

Environment variables

Variable Description Default
PORT Server port 9292
SCENARIO Run a single scenario by name (all)
SPEC_VERSION Filter scenarios by spec version (all)
VERBOSE Show raw JSON output when set (off)
# Run a single scenario
bundle exec rake conformance SCENARIO=ping

# Use a different port with verbose output
bundle exec rake conformance PORT=3000 VERBOSE=1

# Start the server on a specific port
bundle exec rake conformance_server PORT=3000

Start the server and test separately

# Terminal 1: start the server
bundle exec rake conformance_server

# Terminal 2: run all scenarios
npx @modelcontextprotocol/conformance server --url http://localhost:9292/mcp

# Terminal 2: run a single scenario
npx @modelcontextprotocol/conformance server --url http://localhost:9292/mcp --scenario ping

Keeps the server alive between test runs, which avoids the startup overhead when iterating on a single scenario. Stop the server with Ctrl+C when done.

List available scenarios

bundle exec rake conformance_list

Prints all scenario names that can be passed to SCENARIO.

SDK Tier Report

The MCP SDK Tier system requires SDK maintainers to self-assess and report results to the SDK Working Group via modelcontextprotocol/modelcontextprotocol issues.

To generate a full tier assessment report, use the /mcp-sdk-tier-audit slash command from the modelcontextprotocol/conformance repository with the conformance server running:

# Terminal 1 (this repository): start the conformance server
bundle exec rake conformance_server

# Terminal 2 (conformance repository): run the tier audit skill as a slash command in Claude Code
/mcp-sdk-tier-audit /path/to/modelcontextprotocol/ruby-sdk http://localhost:9292/mcp

The skill evaluates conformance pass rate, issue label taxonomy, triage metrics, documentation coverage, and policy compliance, then produces a markdown report suitable for tier advancement submissions.

File Structure

conformance/
  server.rb              # Conformance server (Rack + Puma, default port 9292)
  runner.rb              # Starts the server, runs npx conformance, exits with result code
  expected_failures.yml  # Baseline of known-failing scenarios
  README.md              # This file

Known Limitations

Known-failing scenarios are registered in conformance/expected_failures.yml. They are allowed to fail without affecting the exit code and are tracked to catch regressions. These are shown in the output of bundle exec rake conformance.