The coding agents tracker

Use custom tool calling for one app you own end to end, MCP for any integration you want reused across Claude Code, Cursor, and ChatGPT, and OpenAPI plugins only as a bridge when you already have a spec. MCP is the cross-client standard in 2026; plugins are legacy.

Claude Code wins on raw agent quality and predictable flat pricing, Cursor wins as the editor you live in with the best multi-model routing, and GitHub Copilot wins when the work starts and ends on GitHub. The June 2026 token-billing shift is the tiebreaker for cost.

For a large .NET 11 / C# 14 solution, Claude Code wins on agent quality and runs anywhere a terminal does. Cursor wins if your team wants a GUI and tab completion, as long as you can live without C# Dev Kit. Aider wins on cost and openness.

After an MSIX update, Claude Desktop on Windows reads claude_desktop_config.json from a virtualized path while Edit Config opens the old %APPDATA% one. Edit the file under AppData\Local\Packages\Claude_pzs8sxrjxfjjc and restart.

Anthropic shipped Opus 4.8 on May 28, 2026 with Dynamic Workflows, a research preview in Claude Code that writes a JavaScript orchestration script to run tens to hundreds of subagents in parallel, capped at 1,000 per run.

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.

This banner is a pause, not a failure. It maps to the API's pause_turn stop reason (default 10 server-tool iterations). Click Continue, or in code re-send the assistant response. Full fix here.

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.

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.

Step-by-step guide to the Cursor in Jira integration (launched May 19, 2026): install the Marketplace app, assign a ticket to @Cursor, wire repository access and automation rules, and read the PR the cloud agent links back.

Aider is git-first by default. To edit files outside the repo, pass them on the command line, use /read for reference docs, drop --no-git for unversioned dirs, or symlink. Five working patterns with exact flags.

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.

If you came from Semantic Kernel looking for 'skills,' the Microsoft Agent Framework 1.0 calls them function tools and builds every one from AIFunctionFactory.Create. Here are the three ways to author one in C# -- an inline lambda, a named method, or a class of related tools -- plus what the declarative YAML 'file' approach can and cannot do.

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.

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.

Cursor 3.4 (May 13, 2026) lets one cloud agent environment include multiple repositories, adds Dockerfile build secrets, layer-cached rebuilds that run 70% faster, and an agent-led setup step that validates credentials before the first run.

Copilot Chat reads your .github/copilot-instructions.md fine, but Agent mode and *.instructions.md files often look ignored. Here is the actual checklist: settings, file locations, applyTo globs, and how to prove the file made it into context.

Cursor's Apply silently cancels on big files because the Fast Apply model has an implicit size ceiling. Shrink the edit scope, clean git state, or fall back to a unified diff. Six ranked fixes for Cursor 3.3.

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.

On May 17, 2026 GitHub flipped the default Copilot model on Business and Enterprise plans from GPT-4.1 to GPT-5.3-Codex. GPT-4.1 stays free until June 1, then it falls under usage-based billing. Here is what changes for pinned models in your repo and CI.

A 429 rate_limit_error on claude-sonnet-4-6 in a long agent loop is almost always ITPM, not RPM. Read retry-after, cache the system prompt, and gate on anthropic-ratelimit-input-tokens-remaining. Step-by-step fix with code.

.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.

Aider 0.86 hit the token limit mid-refactor. The fix is /clear, /drop, --map-tokens, and switching to architect mode with Claude Sonnet 4.6's 1M window. Step-by-step repro, error breakdown, and config.

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.

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.

A 2026 walkthrough for wiring RAG into Claude Code 2.1.x: when agentic grep stops scaling, how to attach a hybrid BM25 + dense vector MCP server, how to wrap a retrieval CLI in a custom skill, and how Anthropic's contextual embeddings technique pushes recall above 92%. Anchored to claude-sonnet-4-6, claude-opus-4-7, and Claude Context 0.x.

A 2026 playbook for keeping Claude Code's 200k token context lean in a monorepo: launch from the subtree you are touching, split CLAUDE.md into nested files that load on demand, push path-scoped rules into .claude/rules/, use skills and subagents for the noisy reads, and exclude other teams' files with claudeMdExcludes. Anchored to Claude Code 2.1.x, claude-sonnet-4-6, and claude-opus-4-7.

On May 11, 2026, Cursor shipped effort levels for Bugbot. Default finds 0.7 bugs per review, High pushes it to 0.95, and Custom lets you describe in plain English when each mode should kick in.

Place rolling cache_control breakpoints across messages, respect the 20-block lookback, and refresh the 5-minute TTL automatically so a 50-turn agent loop pays the prefix once, not fifty times. Verified against anthropic 0.42 (Python) and @anthropic-ai/sdk 0.30 (Node) in May 2026.

Cursor 3.3 (May 7, 2026) ships async subagents that work on independent steps of a plan at the same time, a quick action that splits one chat into multiple pull requests, and a redesigned PR workflow that keeps reviews, commits, and changes in one place.

Build a working LLM-as-judge eval harness for a coding agent in Python: golden tasks, deterministic checks, a rubric judge on Claude Sonnet 4.6, calibration against human labels, and a CI gate that fails the build when scores regress.

GitHub deprecated claude-sonnet-4 on May 6, 2026 across Copilot Chat, inline edits, ask and agent modes, and code completions. Recommended migration target is Claude Sonnet 4.6. What to grep for in your repo before the next pinned model selection silently breaks.

Cursor is the best place to plan a refactor. Aider is the best place to execute it from a terminal with cheap models and atomic git commits. This guide shows the exact pipe: dump the Cursor chat to markdown, hand it to Aider as a read-only context file, and run an architect/editor split that finishes the work.

Build a project-scoped Claude Code subagent that drives Playwright in a real browser, scoped to its own MCP server so the main session never sees the 25 browser_* tools. Covers the .claude/agents/browser-tester.md frontmatter, mcpServers inline definition, allowed tool list, isolation: worktree, the Playwright Test Agents init flow, and the Sonnet-vs-Haiku model choice.

Wrap an Agent Framework Workflow in Microsoft.Agents.AI.DurableTask and each executor step is checkpointed. Crash, redeploy, restart - the run continues where it stopped.

Turn the unwritten rules in your repo into a SKILL.md that GitHub Copilot loads on demand. Frontmatter, descriptions that route, file references, and how to verify it actually fires.

Wrap an AIFunction in ApprovalRequiredAIFunction and the agent stops mid-run to ask permission. Here is how the request and response flow works in C#.

Wire a Microsoft.SemanticKernel 1.75.0 plugin into a hosted BackgroundService on .NET 11 and invoke its KernelFunctions on a PeriodicTimer schedule. Covers DI scopes, [KernelFunction] resolution, prompt-cache-friendly invocation, cancellation, and the lifetime gotchas that bite when you move a plugin off the request path.

Claude Code v2.1.128 (May 4, 2026) ships --plugin-dir support for .zip archives, makes EnterWorktree branch from local HEAD, and stops the CLI from leaking its own OTLP endpoint into Bash subprocesses.

Wire an EF Core 10 DbContext into a Model Context Protocol server so Claude Code, Cursor, or any compliant client can run safe, scoped queries against your database. Covers IDbContextFactory lifetime, read-only projections, schema discovery tools, AsNoTracking, parameterised filters, row-level scoping, and the destructive-tool gates you need before letting an agent touch UPDATE.

Cursor's new @cursor/sdk public beta exposes the same runtime, harness, and models that drive the desktop app, CLI, and web UI as a TypeScript package. You get sandboxed cloud VMs, subagents, hooks, MCP, and token-based pricing in a few lines of code.

Claude Code v2.1.126 ships claude project purge, a new CLI subcommand that deletes every transcript, task, file-history entry, and config block tied to a project path in a single shot. Includes --dry-run, --yes, --interactive, and --all.

Wire AIFunctionFactory.Create, ChatOptions.Tools, and ChatClientBuilder.UseFunctionInvocation in Microsoft.Extensions.AI 10.5 so an IChatClient can call your .NET methods automatically. Covers OpenAI and Azure OpenAI providers, the FunctionInvokingChatClient knobs that actually matter (iteration limits, concurrent calls, approval prompts, error handling), and streaming responses with tools.

Microsoft's new Microsoft.AgentGovernance package wraps MCP tool calls with a policy kernel, a security scanner, and a response sanitizer. Here is what each piece does and how the wiring looks in C#.

Take an existing Semantic Kernel plugin with [KernelFunction] methods and turn it into a Model Context Protocol server other agents can call. Covers the drop-in WithTools(kernel) bridge, the native [McpServerTool] rewrite, parameter binding, dependency injection, and the gotchas that bite during the cutover.

Wire up anthropics/claude-code-action@v1 so every pull request gets an autonomous Claude Code review with no @claude trigger. Includes the v1 YAML, claude_args for claude-sonnet-4-6 vs claude-opus-4-7, inline-comment tooling, path filters, REVIEW.md, and the choice between the self-hosted action and the managed Code Review research preview.

Claude Code v2.1.122 adds the ANTHROPIC_BEDROCK_SERVICE_TIER environment variable, sent as the X-Amzn-Bedrock-Service-Tier header. Set it to flex for a 50 percent discount on agent calls or priority for faster responses, without touching SDK code.

Stream Claude responses from an ASP.NET Core 11 minimal API end-to-end: the official Anthropic .NET SDK, TypedResults.ServerSentEvents, SseItem, IAsyncEnumerable, cancellation flow, and the gotchas that buffer your tokens silently. With Claude Sonnet 4.6 and Opus 4.7 examples.

cowork-terminal-mcp v0.4.1 bridges Claude Cowork's sandboxed VM to your host shell. One tool, stdio transport, hard-pinned Git Bash on Windows.

A practical guide to turning the JSONL files Claude Code writes under ~/.claude/projects/ into shareable PDFs using jsonl-to-pdf, with sub-agent nesting, secret redaction, compact and dark themes, and CI-friendly batch recipes.

Add prompt caching to a Python or TypeScript Anthropic SDK app, place cache_control breakpoints correctly, and read cache_read_input_tokens and cache_creation_input_tokens to compute a real hit rate. With pricing math for Claude Sonnet 4.6 and Opus 4.7.

A 2026 playbook for CLAUDE.md files that Claude Code actually follows: the 200-line target, when to use path-scoped rules in .claude/rules/, @import hierarchy and 5-hop max depth, the user-message vs system-prompt gap, the line between CLAUDE.md and auto memory, and when to give up and write a hook instead. Anchored to Claude Code 2.1.x and verified against the official memory docs.

Claude Code v2.1.119 expands --from-pr beyond github.com. The CLI now accepts GitLab merge-request, Bitbucket pull-request, and GitHub Enterprise PR URLs, and a new prUrlTemplate setting points the footer PR badge at the right code-review host.

Three ways to put Claude Code on a schedule that triages GitHub issues unattended in 2026: cloud Routines (the new /schedule), the claude-code-action v1 with cron + issues.opened, and the session-scoped /loop. Includes a runnable Routine prompt, a complete GitHub Actions YAML, jitter and identity gotchas, and when to pick which.

GitHub Copilot for VS Code shipped Bring Your Own Key on April 22, 2026. Wire your own Anthropic, OpenAI, Gemini, OpenRouter, or Azure account into Chat, or point at a local Ollama or Foundry Local model. Billing skips the Copilot quota and goes straight to the provider.

Build a working Model Context Protocol server in C# 14 / .NET 11 using the official ModelContextProtocol 1.2 SDK. Covers stdio transport, [McpServerTool] attributes, dependency injection, the stderr logging trap, and registration with Claude Code, Claude Desktop, and VS Code.

Build a working Model Context Protocol server in Python using the official mcp 1.27 SDK and FastMCP. Covers Pydantic schemas, the stdio stdout trap, mcp dev / mcp install, and registration with Claude Desktop and Claude Code.

Step-by-step guide to wrapping any command-line tool as a Model Context Protocol server using the TypeScript SDK 1.29. Covers the stdout trap, child_process patterns, error propagation, and a full working git server.

Visual Studio 2022 17.14.30 bundles the Azure MCP Server into the Azure development workload. Copilot Chat can hit 230+ Azure tools across 45 services without installing a thing.

Visual Studio 18.5 GA ships a guided Debugger Agent workflow in Copilot Chat that forms a hypothesis, sets breakpoints, rides along through a repro, validates against runtime state, and proposes a fix.

Visual Studio 2026 18.5.0 lets GitHub Copilot load Agent Skills from .github/skills, .claude/skills, and ~/.copilot/skills. Reusable SKILL.md instruction packs travel with your repo.

GitHub Copilot Modernization is pitched as an Assess, Plan, Execute loop for migrating legacy .NET apps. The assessment phase is where the value lives: an inventory report, categorized blockers, and file-level remediation guidance you can diff like code.

Microsoft Agent Framework hits 1.0 with stable APIs, multi-provider connectors, multi-agent orchestration, and A2A/MCP interop. Here is what it looks like in practice on .NET 10.

The .NET team shares ten months of real data on running GitHub's Copilot Coding Agent in dotnet/runtime: 878 PRs, a 67.9% merge rate, and clear lessons on where AI-assisted development helps and where it still falls short.

Microsoft's free generative AI course for .NET developers ships Version 2, rebuilt for .NET 10 and migrated from Semantic Kernel to Microsoft.Extensions.AI's IChatClient pattern.

How to wire Model Context Protocol (MCP) servers in C# on .NET 10 using microsoft/mcp. Covers tool contracts, input validation, auth, observability, and production-readiness patterns.