Match the shape of CallToolResult schema

[cetra3]

Adjusts the content field to always be present

Motivation and Context

The MCP schema has the content field as mandatory: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/3b3874b4fc010f34ef5b106f044a4867534a9499/schema/2025-06-18/schema.ts#L782

Some of the MCP implementations (I.e, zed editor) assume (& rightly so) that this field is always present.

How Has This Been Tested?

Running tests

Breaking Changes

It is essentially a breaking change on the type CallToolResult

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[Copilot]

Pull Request Overview

This PR modifies the CallToolResult schema to make the content field mandatory and always present, aligning with the MCP (Model Context Protocol) schema specification. The change ensures compatibility with MCP implementations that expect the content field to always exist.

Key changes:

• Changed content field from Option<Vec<Content>> to Vec<Content> in the CallToolResult struct
• Updated JSON schema to make content a required field and remove null type
• Updated all test code to work with the non-optional content field

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
crates/rmcp/src/model.rs	Modified CallToolResult struct to make content field mandatory and updated related methods
crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json	Updated JSON schema to make content required and remove null type
crates/rmcp/tests/test_tool_macros.rs	Updated test code to handle non-optional content field
crates/rmcp/tests/test_structured_output.rs	Updated test assertions and content access for mandatory content field

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[Copilot]

The pattern match (None, Some(contents)) is unreachable because self.content is now a Vec<Content> (not Option<Vec<Content>>), so it can never be Some(contents). This should be (None, contents) and the condition should check if contents is not empty.

[Copilot]

The variable contents is now of type &Content (from first()) rather than &Vec<Content>, so calling contents.as_text() directly is incorrect. This should be accessing the first content item's text method.

[4t145]

fix ci please

[4t145]

thanks