[BUG] [v0.0.7] cortex-mcp-types SamplingRequest accepts embedded resource content even though sampling messages only allow text or image

[marvinayisi]

Project

cortex

Description

A sampling request whose message content is an embedded resource deserializes successfully into SamplingRequest, even though the 2024 MCP schema limits sampling messages to text or image content.

Error Message

SAMPLING_REQUEST_RESOURCE_PARSE=Ok(SamplingRequest { messages: [SamplingMessage { role: User, content: Resource { resource: ResourceContent { uri: "file:///tmp/demo.txt", mime_type: None, text: Some("hello"), blob: None } } }], model_preferences: None, system_prompt: None, include_context: None, temperature: None, max_tokens: Some(64), stop_sequences: None, metadata: None })

Debug Logs

N/A

System Information

Cortex crate: cortex-mcp-types 0.0.7
Commit: 7954d02
Date: 2026-04-10
OS: macOS

Screenshots

https://github.com/marvinayisi/issue-images/blob/main/mcp-sampling-request-resource-20260410-074112.png

Steps to Reproduce

1. Create a tiny Rust crate depending on cortex-mcp-types from this workspace.
2. Deserialize a SamplingRequest whose message content has type: "resource".
3. Print the parse result.

Expected Behavior

The invalid sampling message content should be rejected.

Actual Behavior

Deserialization succeeds and produces a SamplingRequest containing resource content.

Additional Context

• Authoritative spec: https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/refs/heads/main/schema/2024-11-05/schema.ts
• Code path: /Users/odeili/Projects/platform/cortex/src/cortex-mcp-types/src/sampling.rs
• Duplicate check on 2026-04-10:
• cortex-mcp-types SamplingRequest resource content accepted