Claude Code sometimes only shows `Error: MCP error -32603: Internal error`
when an unexpected exception occurs during a tool call.
This change broadens the exception handling scope so the server can surface
the exception message more often, making failures easier to diagnose.
The "Component definition patterns" section has been removed because it overlaps with
"Three Ways to Define Components" in AGENTS.md:
d745ccde/AGENTS.md (key-patterns)
This helps make the system prompt more concise.
Ruby 4.0.0 has been released, so this PR adds Ruby 4.0 to CI.
https://www.ruby-lang.org/en/news/2025/12/25/ruby-4-0-0-released/
To prevent the CI label from showing "CI / Test Ruby 4" instead of
"CI / Test Ruby 4.0", the matrix entries are changed from floats to strings.
This raises an exception when duplicate tool names are registered,
instead of silently overwriting tools. Tool names are required to be
unique within a server, so this behavior aligns with the MCP specification.
> Tool names SHOULD be unique within a server.
https://modelcontextprotocol.io/specification/2025-11-25/server/tools#tool-names
Validation for tool names could be made more strictly spec-compliant in a separate effort.
Fixes#197
This PR adds support for the optional `websiteUrl` parameter in `serverInfo`.
This parameter has been supported since the 2025-11-25 MCP specification.
This PR also implements part of https://github.com/modelcontextprotocol/ruby-sdk/issues/127.
This refactoring extracts common schema validation logic into a base Schema
class, eliminating ~100 lines of duplicate code between InputSchema and
OutputSchema. It also adds support for the JSON Schema `additionalProperties`
keyword to allow fine-grained control over extra properties in tool arguments.
Previously `additionalParameters` could be set only on OutputSchema.
Key changes:
- Created MCP::Tool::Schema base class consolidating:
- Schema validation against JSON Schema Draft 4 metaschema
- Deep key transformation (string to symbol conversion)
- $ref disallowance checking
- Common validation methods
- Refactored InputSchema to inherit from Schema:
- Simplified constructor to accept full schema hash
- Changed required fields storage from symbols to strings
- Removed ~40 lines of duplicated validation logic
- Refactored OutputSchema to inherit from Schema:
- Removed ~54 lines of duplicated validation logic
- Now shares all common functionality with InputSchema
- Updated Tool.input_schema setter:
- Simplified to pass full hash directly to InputSchema
- Added additionalProperties support:
- By default, tools now allow additional properties (JSON Schema default)
- Can explicitly set `additionalProperties: false` to disallow extras
- Added comprehensive test coverage for both behaviors
When starting an MCP server in Claude Code with `protocol_version` set to `DRAFT-2025-v3`,
it fails with the following error:
```console
2025-12-04T02:58:01.548Z [DEBUG] MCP server "example": Connection failed after 2093ms: Server's protocol version is not supported: DRAFT-2025-v3
2025-12-04T02:58:01.548Z [ERROR] MCP server "example" Connection failed: Server's protocol version is not supported: DRAFT-2025-v3
```
This PR changes the default behavior so that if `protocol_version` is not specified,
it uses the latest stable protocol version instead of the draft version.
This PR also updates the README to note that the latest stable protocol version includes
new features from the draft version.
This PR updates the specification URL to `latest`.
This change avoids the need to update the URL whenever a new protocol version is released.
The `latest` path redirects to the latest protocol version.
This PR fixes incorrect examples in README.md. The block variable could be removed if it is unused,
but when presenting an example `:server_context` should still be shown as a keyword argument.
Fixes#185.
Follow-up to #175.
Since `json_rpc_handler` was merged in #175, it has been removed from AGENTS.md.
The "Dependencies" section was also removed because the information there would have become redundant.
This adds automated deployment of a versioned API documentation landing
page using GitHub Pages. The landing page links to documentation hosted
on RubyDoc.info, the de facto standard documentation site for the Ruby
ecosystem. The landing page will update to reflect new releases.
Changes
-------
1. **Documentation generation script** (see `bin/generate-gh-pages.sh`)
Copies and commits documentation files to the gh-pages branch. The
script uses git worktrees to isolate the process from the main
workspace.
The script:
- Creates the gh-pages branch as an orphan branch if it doesn't exist
- Parses semantic versions from tag names, ignoring arbitrary
prefixes (e.g., tags `1.2.3`, `v1.2.3`, and `release-1.2.3` all
create `v1.2.3`)
- Determines the latest version using semantic version sorting
- Copies static Jekyll template files from `docs/` to the gh-pages
root (for the latest version only)
- Generates `docs/_data/versions.yml` with a list of all versions
for the Jekyll templates to consume
2. **Jekyll template files** (see `docs/` directory)
- `docs/_config.yml` - Jekyll configuration
- `docs/index.md` - Landing page template that links to all versions
on RubyDoc.info based on generated `docs/_data/versions.yml`
- `docs/latest/index.html` - Redirect page template that redirects
to the latest documentation on RubyDoc.info
3. **GitHub Actions workflow** (see `.github/workflows/release.yml`)
Added a `publish_gh_pages` job that runs after the `publish_gem` job
on release events. The job invokes the generation script with the
release tag name, then pushes the updated gh-pages branch to deploy
the documentation.
4. **CI validation** (see `.github/workflows/ci.yml`)
Added a `yard` job that runs YARD validation with `--no-output`.
This ensures YARD can successfully parse the codebase (without
generating output), catching documentation issues early in CI.
5. **YARD dependencies** (see `Gemfile`)
Added `yard` and `yard-sorbet` gems as development dependencies to
support documentation validation in CI.
YARD documentation is automatically generated and hosted by
RubyDoc.info when the gem is published to RubyGems.org.
6. **Documentation links** (see `README.md` and `mcp.gemspec`)
Added links to the published API documentation on RubyDoc.info in
the README and gemspec metadata.
Documentation URL
-----------------
Custom documentation will be available at:
https://modelcontextprotocol.github.io/ruby-sdk/
RubyDoc.info documentation will be accessible at:
- https://rubydoc.info/gems/mcp (latest version)
- https://rubydoc.info/gems/mcp/1.2.3 (specific versions)
Co-Authored-By: Claude <noreply@anthropic.com>
Consolidates four identical constructions of error `Tool::Response` in
`handle_call_tool_request` into a single private `error_tool_response` method,
reducing duplication and improving maintainability. No behavior change.
For example, the `title` introduced in #109 is not supported in the latest stable protocol version "2025-06-18":
https://modelcontextprotocol.io/specification/2025-06-18
It is supported in the Draft of the next version:
https://modelcontextprotocol.io/specification/draft
In other words, the fact that the Ruby SDK treats "2025-06-18" as the default protocol version while `title` is
only supported in the Draft results in an inconsistency.
Because of this, a new version `"Draft"` has been added to the list of supported versions.
Its value follows the schema below and is defined as `DRAFT-2025-v3`:
14ec41c/schema/draft/schema.ts (L15)
It was also considered to continue using the latest stable version "2025-06-18" as the Ruby SDK default instead of the Draft.
However, in that case, users would need to explicitly specify `MCP::Server.new(protocol_version: 'DRAFT-2025-v3')`,
which adds extra burden. In this PR, Draft is made the default in order to provide the following benefits:
- Users are likely to prefer using the Draft version over the latest stable version
- No need to specify the `protocol_version` option when initializing `MCP::Server`
- Users generally do not need to know the internal development value `DRAFT-2025-v3`
The primary case for specifying `protocol_version` explicitly is when strict adherence to a particular version is required.
However, it seems more practical to prioritize use cases where backward-compatible features, including those from the Draft,
are desirable. This is the rationale behind making the Draft version the default.
In addition, making the Draft version the default protocol version preserves backward compatibility for `MCP::Server`.
NOTE: `DRAFT-2025-v3` is a development code, so its value cannot be set externally.
It is applied either when `protocol_version` is omitted or when `nil` is set explicitly,
such as with `MCP::Configuration.new(protocol_version: nil)`.
This prevents users from creating implementations that depend on development codes like `DRAFT-2025-v3`.
