MCP Client Compatibility¶

This page tracks the compatibility status of various MCP clients with the EcoSemantic MCP server. We regularly test different clients and update this documentation as the MCP ecosystem evolves.

Last Updated

November 27, 2025 - Initial compatibility testing completed.

Compatibility Matrix¶

OAuth 2.1 Authentication¶

Client	Version	Connect	List Tools	Tool Calls	Status	Notes
Claude.ai	Web	✅	✅	✅	Working	Full OAuth 2.1 flow supported
Claude Desktop	Latest	✅	✅	✅	Working	Recommended client
VSCode Copilot	1.99+	✅	✅	✅	Working	Via MCP extension
MCP Inspector	0.9.x	✅	❌	❌	Partial	Bug #358 - OAuth not triggered on 401 with Streamable HTTP

API Token Authentication¶

Client	Version	Connect	List Tools	Tool Calls	Status	Notes
VSCode MCP Extension	Latest	✅	✅	✅	Working	Full functionality
Claude Code	Latest	✅	✅	✅	Working	Via mcp-remote or direct
Google Antigravity	Latest	✅	✅	❌	Partial	Bug #2489 - Tool calls stall indefinitely
MCP Inspector	0.9.x	✅	❌	❌	Partial	Connection issues with remote Streamable HTTP
Cursor	Latest	🔄	🔄	🔄	Untested	Awaiting testing
Windsurf	Latest	🔄	🔄	🔄	Untested	Awaiting testing

Status Legend¶

Symbol	Meaning
✅	Working correctly
❌	Not working / Failed
⚠️	Working with limitations
🔄	Untested / Pending

Detailed Test Results¶

Claude.ai (Web Interface)¶

Fully Working

Last Tested: November 27, 2025

Authentication: OAuth 2.1

Test Results:

[x] OAuth discovery (.well-known endpoints)
[x] Dynamic client registration
[x] Authorization flow with PKCE
[x] Token exchange
[x] Session establishment
[x] Tool listing (31 tools)
[x] Tool execution
[x] Token refresh

Configuration:

MCP Server URL: https://mcp.ecosemantic.com/mcp

VSCode MCP Extension¶

Fully Working

Last Tested: November 27, 2025

Authentication: API Token

Test Results:

[x] Connection with Bearer token
[x] Session establishment
[x] Tool listing
[x] Tool execution
[x] Multiple sequential calls

Configuration:

{
  "mcpServers": {
    "EcoSemantic": {
      "serverUrl": "https://mcp.ecosemantic.com/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_TOKEN",
        "Content-Type": "application/json"
      }
    }
  }
}

Google Antigravity¶

Partial - Tool Calls Fail

Last Tested: November 27, 2025

Authentication: API Token

Test Results:

[x] Connection established
[x] Tool listing (31 tools visible)
[ ] Tool execution - FAILS

Known Issue:

Tool calls stall indefinitely with error:

connection closed: calling "tools/call": client is closing: 
standalone SSE stream: failed to reconnect

This is a known Antigravity bug affecting remote MCP servers. See FastMCP Issue #2489.

Workaround: Use Claude Code or VSCode MCP extension instead.

MCP Inspector¶

Partial - Connection Issues

Last Tested: November 27, 2025

Authentication: OAuth 2.1 / API Token

Test Results (OAuth):

[x] OAuth flow completes successfully
[x] Access token issued
[ ] Connection after OAuth - FAILS

Test Results (API Token):

[ ] Connection with Bearer token - FAILS

Known Issues:

OAuth + Streamable HTTP: OAuth flow doesn't trigger on 401 response. See Inspector Issue #358.
General: "Connection Error - Check if your MCP server is running and proxy token is correct"

Note: MCP Inspector works best with local servers or SSE transport. Remote Streamable HTTP servers have compatibility issues.

Server Configuration¶

EcoSemantic MCP server uses:

Transport: Streamable HTTP (/mcp endpoint)
Authentication: Dual support for OAuth 2.1 and API tokens
Protocol Version: MCP 2025-06-18

Reporting Issues¶

If you encounter compatibility issues with a client not listed here, please:

Check the Known Issues section below
Report to our Feedback Portal
Include client name, version, and error messages

Known Issues¶

Token Refresh Race Condition¶

Some clients that aggressively refresh OAuth tokens may experience intermittent 401 errors due to token rotation timing. This affects:

MCP Inspector (when OAuth flow succeeds but subsequent requests fail)

Status: Under investigation

Streamable HTTP Compatibility¶

Some older MCP clients expect SSE transport at /sse endpoint. EcoSemantic uses the modern Streamable HTTP transport at /mcp.

Affected Clients:

Legacy MCP clients expecting SSE
Some proxy configurations

Version History¶

Date	Changes
2025-11-27	Initial compatibility matrix published
	Tested: Claude.ai, VSCode, Antigravity, MCP Inspector