MCP Protocol Validation Error: All tools have invalid inputSchema.type (not "object")

[pelby]

Environment

• MCP Client: Claude Code v2.0.49 via Super-MCP router
• Package: @adeze/raindrop-mcp (latest from npm via npx -y)
• OS: macOS (Darwin 24.6.0)
• Node: via npx
• Installation method: npx -y @adeze/raindrop-mcp

Related Issues

This appears related to #37 and the fix attempts in PR #38 and PR #40. I'm providing additional diagnostic details that may help with the fix.

Description

When attempting to use the raindrop-mcp server through Super-MCP, all 10 tools fail MCP protocol validation. The server starts successfully and connects via STDIO, but tool schemas don't conform to the MCP specification requirement that inputSchema.type must be "object".

Error Message

MCP error -32603: [
{
"code": "invalid_literal",
"expected": "object",
"path": ["tools", 0, "inputSchema", "type"],
"message": "Invalid literal value, expected object"
},
{
"code": "invalid_literal",
"expected": "object",
"path": ["tools", 1, "inputSchema", "type"],
"message": "Invalid literal value, expected object"
},
// ... (repeated for all 10 tools: diagnostics, collection_list, collection_manage,
// bookmark_search, bookmark_manage, tag_manage, highlight_manage,
// getRaindrop, listRaindrops, bulk_edit_raindrops)
]

Expected Behaviour

According to the MCP specification, tool inputSchema must have type: "object":

{
  "type": "object",
  "properties": { ... },
  "required": [ ... ]
}

Actual Behaviour

• ✅ Server starts successfully: "MCP server connected via STDIO transport"
• ✅ API token validated: direct API test successful (GET /rest/v1/user returns 200)
• ✅ Package detected by Super-MCP
• ❌ All 10 tools fail schema validation
• ❌ Tools cannot be called due to validation errors

Steps to Reproduce

1. Configure MCP client to launch: npx -y @adeze/raindrop-mcp
2. Set RAINDROP_ACCESS_TOKEN environment variable (valid test token)
3. Server connects successfully via STDIO
4. Attempt to list tools → all 10 show schema validation errors
5. Attempt to call any tool (e.g., diagnostics) → receives validation error

Verification Steps Taken

✅ API Token Works:

curl -H "Authorization: Bearer <token>" https://api.raindrop.io/rest/v1/user
# Returns 200 OK with user data

✅ Package Runs:

RAINDROP_ACCESS_TOKEN=<token> npx -y @adeze/raindrop-mcp
# Output: [2025-11-21T18:08:04.982Z] INFO [mcp-stdio] MCP server connected via STDIO transport

✅ Comparison with Working Package:

Switched to raindrop-mcp (egoist version) with identical configuration → works correctly with properly formatted schemas.

Impact

This prevents the package from being usable with any MCP-compliant client that validates tool schemas according to the specification.

Additional Context

Working with Claude Code:

I'm debugging this issue with assistance from Claude Code and may attempt a fix. If successful, I'll submit a PR referencing this issue.

Why This Package Matters:

The @adeze/raindrop-mcp package has significantly more features than alternatives (bulk operations, tag management, collection restructuring, highlights), making it worth fixing rather than switching to simpler alternatives.

Thank you for your work on this project! 🙏