According to the specification, `destructive_hint`, `idempotent_hint`, `open_world_hint`,
and `read_only_hint` of `ToolAnnotations` are optional with default values:
https://modelcontextprotocol.io/specification/2025-06-18/schema#toolannotations
This PR sets their default values in accordance with the specification.
Additionally, for readability, the hints have been reordered to follow the specification.
The tests related to `MCP::Tool::Annotations` will be extracted from the `MCP::ToolTest` test class
into a dedicated `MCP::Tool::AnnotationsTest` unit test class as a testing pair.
This improves test clarity, file level test independence, and file level execution speed.
It also ensures consistent placement as a testing pair under `MCP::Tool::*`:
```console
$ ls lib/mcp/tool/
annotations.rb input_schema.rb response.rb
$ ls test/mcp/tool/
annotations_test.rb input_schema_test.rb response_test.rb
```
Follow-up to #109.
The introduction of `title` in #109 is still a draft and is not supported in the latest specification, `Version 2025-06-18 (latest)`.
In this PR, the README.md will be updated to mention this point and restore the references to the removed `annotations.title`.
This aims to inform users that, as of `Version 2025-06-18 (latest)`, the use of `annotations.title` is considered stable.
Additionally, separate validation for these parameters could be added.
Please refer to the following comment regarding `annotations.title` and `title`:
https://github.com/modelcontextprotocol/modelcontextprotocol/pull/663#issuecomment-2963519737
Both the combination of positional argument and naming does not feel
like Ruby.
This change makes `is_error` argument a keyword argument called `error`.
Thanks to this, the usage is more self-explanatory:
```ruby
response = Response.new([], error: true)
```
When defining a tool without any arguments taken, it should be allowed
to not have to define the `input_schema` at all, and the default value
for such a scenario should be `{ type: "object" }` as per the schema.
16d91abb68/schema/2025-06-18/schema.ts (L896-L900)
- Updated `call` method in `MCP::Tool` and `MCP::Prompt` to accept `server_context` as an optional parameter.
- Refactored `MCP::Server` to streamline argument handling for tool and prompt calls, introducing helper methods `call_tool_with_args` and `call_prompt_template_with_args`.
- Adjusted tests to reflect changes in method signatures and ensure compatibility with optional `server_context` parameter.
