fix(tool): remove unnecessary schema validation

[4t145]

1. remove unnecessary schema validation
2. add a method directly convert the structured output into typed data.

Motivation and Context

We don't really need to do the validation in rust, because deserilization already is a validation. And if user want to do the validation, they can use the jsonschame crate.

And also, the original validation method is a wrong implementation, as I mentioned in #374

How Has This Been Tested?

Breaking Changes

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

[4t145]

@ccamel55 please review this. I didn't notice the problem when I merge the pr.

[Copilot]

Pull Request Overview

This PR removes unnecessary JSON schema validation from the tool system and introduces a type-safe conversion method for structured outputs. The changes eliminate redundant validation since Rust's deserialization already provides type safety, and replace it with a more idiomatic approach.

Key changes:

• Removes schema validation functions and related validation logic
• Adds into_typed() method to CallToolResult for type-safe conversion of structured content
• Updates tests to use the new type-safe approach instead of validation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
crates/rmcp/src/model.rs	Replaces validation method with into_typed() for type-safe conversion and simplifies deserialization validation
crates/rmcp/src/handler/server/tool.rs	Removes schema validation functions (validate_against_schema and get_json_value_type)
crates/rmcp/src/handler/server/router/tool.rs	Removes schema validation logic from tool call execution
crates/rmcp/tests/test_structured_output.rs	Updates test to use new into_typed() method instead of validation

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

This line will always attempt to deserialize null into type T, which will likely fail for most types. Consider returning an error indicating that no structured content or valid text content was found instead of trying to deserialize null.

Suggested change

	serde_json::from_value(serde_json::Value::Null)
	Err(serde_json::Error::custom("No structured content or valid text content found"))

[Copilot]

[nitpick] The logic for extracting content could be simplified. The current implementation checks for text content only in the first element of the content array. Consider making this behavior more explicit or handling multiple content items if that's the intended behavior.

Suggested change

	Some(text)
	// Collect all text content from the vector
	let texts: Vec<&str> = contents.iter()
	.filter_map(|c| c.as_text().map(|t| t.text.as_str()))
	.collect();
	if !texts.is_empty() {
	// Concatenate all text content with a space separator
	Some(texts.join(" "))

[Copilot]

The method only considers the first content item when extracting text. This behavior should be documented in the method's docstring to clarify that only the first text content will be used for deserialization.

[ccamel55]

LGTM but wouldn't this technically be a breaking change since it removes public facing API? I'll leave it to the maintainers to to decide though 😄

[4t145]

@ccamel55 It's ok to introduce breaking changes, we haven't release the deleted api.

[jokemanfire]

It can be Deserialized , so it is structed json data, If I understand it ?