Fix: GitHub MCP server tool calls fail silently when the PAT isn't passed
GitHub MCP tools show up but every call returns empty or 'Bad credentials'? The token is unset. Put the PAT in the env block, verify with curl, done.
Tag: mcp
42 posts · Page 3 of 5
The Dart and Flutter MCP server: one command to give Claude Code your running Flutter app
Dart 3.12 ships dart mcp-server, the official MCP bridge into the Dart and Flutter toolchain. Register it once in Claude Code, Cursor, or Codex CLI and your agent gets hot reload, pub.dev search, and live widget introspection without copy-pasting a DTD URI.
Fix: HTTP MCP Server URL Won't Connect in Claude Desktop (stdio vs HTTP Transport)
Claude Desktop's claude_desktop_config.json only validates stdio servers. Drop a 'url' field in and it silently strips the entry, crashes on startup, or boots with zero tools. Use a custom connector for remote URLs and mcp-remote as a stdio bridge for local HTTP servers.
How to Reduce the Number of MCP Tools Claude Loads to Avoid the Tool-Use Limit
Five MCP servers can burn 55k tokens and wreck tool-selection accuracy before Claude does any work. How to fix it in Claude Code 2.1.x with ENABLE_TOOL_SEARCH and alwaysLoad, on the raw API with the tool search tool and defer_loading, and on the MCP connector with mcp_toolset. Anchored to claude-opus-4-7, claude-sonnet-4-6, and the 20251119 tool search variants.
Fix: Extra Inputs Are Not Permitted on a Tool Call With a Structured Argument
Your agent's tool call fails with Pydantic's 'Extra inputs are not permitted'. The model added a field your structured argument forbids. Turn on strict tool use so the grammar blocks it, relax the validator, or recover in the loop.
Fix: `ECONNREFUSED` When a Local MCP Server Starts Before the Client Is Ready
ECONNREFUSED from an MCP client means nothing was listening on that host:port yet. Fix the startup race, the localhost IPv4/IPv6 trap, and wrong-port mistakes for HTTP MCP servers.
Fix: Claude Code Reports `MCP server disconnected` Inside WSL
Why Claude Code shows 'MCP server disconnected' or 'Connection closed' for a working MCP server when launched from WSL2. Covers stdio spawning across the Windows/Linux boundary, npx and node ENOENT, mirrored networking for HTTP servers, VMMem reaping, and how to diagnose the right one with claude --debug.
dotnet new mcpserver Now Ships in the .NET 11 Preview 4 SDK
.NET 11 Preview 4 bundles the mcpserver project template directly into the SDK. No separate Microsoft.McpServer.ProjectTemplates install, no preview feed dance. Pick stdio or HTTP transport, opt into Native AOT, and dotnet new mcpserver -o MyServer is the whole setup.
Fix: Tool Call Arguments Did Not Match Schema in Anthropic Tool Use
Why your Claude tool call fails schema validation, in both flavours: the API rejecting your tool definition at request time, and Claude returning a tool_use block your runner cannot accept. Concrete fixes for each, with strict mode, oneOf/anyOf, additionalProperties, and the retry loop pattern.
Fix: MCP Server stdio Hang When Launched From Claude Code
Why your Model Context Protocol server gets stuck in 'connecting' from Claude Code 2.x and never registers any tools. Covers stdout pollution, the npx install prompt, MCP_TIMEOUT, buffered output, and WSL pitfalls, with verifiable repros.