Tag: mcp

ModelContextProtocol 2.3.0, released October 20, 2026, changes McpClient.ServerInfo from Implementation to Implementation? because 2026-07-28 servers may omit their identity from server/discover. Here is why, what breaks under warnings-as-errors, and the one-line fix.

Wire Cursor Rollouts (launched September 23, 2026) to your CI and to Datadog so every PR, including the ones a cloud agent wrote, gets a rollout plan before merge and per-environment checks at deploy, 20 minutes, 1 hour, 1 day and 3 days. Covers the DeploymentsService API, a GitHub Actions job, the Datadog MCP data source, and the gotchas that leave changes stuck in Pending.

Azure MCP Server 3.0.0 shipped on October 12, 2026. Tool calls with unknown parameters now fail, options like subscription and tenant were removed from many tools, new Storage accounts disable Shared Key auth, and the server speaks the stateless MCP 2026-07-28 protocol.

The GitHub Copilot SDK (1.0.18, October 8, 2026) is a thin client for the Copilot CLI runtime: your app speaks JSON-RPC to the same agent loop that powers Copilot CLI, with built-in file and shell tools, MCP, sub-agents, hooks, and BYOK. How it is wired, four things you can build with it, and the defaults that will bite you in production.

MCP is a JSON-RPC protocol that lets any AI host call tools, read resources and use prompts from any server, the way LSP did for language support. Here is how it works on the wire under revision 2026-07-28, captured from a real server, and why VS Code, Visual Studio, JetBrains, Xcode, Zed and Cursor all converged on it.

Every agent request pays for its system prompt, the provider's hidden tool-use preamble, and every tool schema before the user says anything. How to measure that fixed cost with differential count_tokens calls on the Anthropic API, the input_tokens endpoint on OpenAI, an MCP listTools probe, and /context in Claude Code, anchored to claude-opus-5-5, claude-sonnet-5, and @modelcontextprotocol/client 2.1.0.

Scoping a token does not stop a prompt-injected agent from leaking it. Moving the token out of the agent's process does. Three working setups: a 50-line gateway any agent can call, Claude Code 2.1.199+ sandbox masking with injectHosts, and Claude Managed Agents vaults, plus the measured leak that host-level injection still allows.

Move a local stdio MCP server to a remote Streamable HTTP server behind OAuth on MCP spec 2026-07-28 and TypeScript SDK 2.0.0. Dynamic Client Registration is now deprecated, so use Client ID Metadata Documents first and keep DCR only as a fallback. Covers the steps, a measured CIMD/DCR test matrix, and the misleading error you get when the two sides disagree.

Your MCP URL 307/308-redirects to another host, the client follows it, the Authorization header is stripped, and the target answers 401. Register the final URL.

OAuth succeeded but every MCP call gets 401 invalid_token? Make the PRM resource, the token's aud and your validator agree on one canonical server URL.