# MCP Server Catalog

Chapter 10 of Loop Engineering uses a nervous-system analogy for MCP while keeping its boundary clear: MCP is exchange infrastructure, not judgment, governance, security, or memory. Use the live catalog below to compare current servers, adopters, and capabilities.

Each entry below is verified against the cited upstream source. Rows are grouped by category. Refreshed quarterly; next review 2026-09.

### Reference clients and protocol authority

                        Vendor / project
                        What it exposes
                        Client compatibility
                        Source
                        Verified

                        Anthropic - Claude Desktop / Claude Code
                        Reference MCP client. Configurable via claude_desktop_config.json to connect to any compliant MCP server (filesystem, git, databases, search, etc.).
                        n/a - this is the reference client.
                        [modelcontextprotocol.io](https://modelcontextprotocol.io/)
                        2026-06

                        MCP specification
                        The protocol itself: JSON-RPC 2.0 over stdio or HTTP-SSE; resources, tools, prompts, and sampling primitives.
                        Any compliant client.
                        [spec.modelcontextprotocol.io](https://modelcontextprotocol.io/specification)
                        2026-06

### Vendor adopters (named in the launch announcement)

The following vendors were named in [Anthropic's MCP launch announcement (November 25, 2024)](https://www.anthropic.com/news/model-context-protocol) as early adopters integrating MCP into their products.

                        Vendor / project
                        What it exposes
                        Client compatibility
                        Source
                        Verified

                        Block
                        Internal developer-tooling exposure for agentic systems. Named in launch as an early adopter integrating MCP into agentic systems.
                        Internal Block tooling; per launch announcement.
                        [launch announcement](https://www.anthropic.com/news/model-context-protocol)
                        2026-06

                        Apollo
                        GraphQL schema and operations exposed via MCP server. Named in launch as integrating MCP for AI access to Apollo's GraphQL platform.
                        Any MCP client.
                        [launch announcement](https://www.anthropic.com/news/model-context-protocol) · [apollographql.com](https://www.apollographql.com/)
                        2026-06

                        Zed
                        Editor-native MCP client. Zed's assistant panel connects to MCP servers for context-aware code assistance.
                        n/a - Zed is itself an MCP client surface.
                        [zed.dev](https://zed.dev/) · [launch announcement](https://www.anthropic.com/news/model-context-protocol)
                        2026-06

                        Replit
                        Workspace and run-environment exposure for AI agents working inside Replit projects. Named in launch as integrating MCP into the Replit AI experience.
                        Replit AI surfaces.
                        [replit.com](https://replit.com/) · [launch announcement](https://www.anthropic.com/news/model-context-protocol)
                        2026-06

                        Codeium / Windsurf
                        IDE MCP client surface for connecting Codeium / Windsurf to compliant MCP servers (filesystem, repo intelligence, custom backends).
                        Windsurf IDE; per launch announcement.
                        [codeium.com](https://codeium.com/) · [launch announcement](https://www.anthropic.com/news/model-context-protocol)
                        2026-06

                        Sourcegraph
                        Code intelligence exposed via MCP server (cross-repo search, symbol navigation, definitions, references) for AI assistants. Named in launch.
                        Any MCP client.
                        [sourcegraph.com](https://sourcegraph.com/) · [launch announcement](https://www.anthropic.com/news/model-context-protocol)
                        2026-06

### Community reference servers (modelcontextprotocol/servers)

The [official MCP servers repository](https://github.com/modelcontextprotocol/servers) hosts a maintained set of reference and community-contributed servers. The catalog grows continuously; the entries below are widely deployed reference servers as of the verified date.

                        Server
                        What it exposes
                        Notes
                        Verified

                        mcp-server-filesystem
                        Read / write access to a local filesystem subtree.
                        Path-scope is enforced server-side; the client cannot escape the configured root.
                        2026-06

                        mcp-server-git
                        Git operations (status, log, diff, blame) on a local repository.
                        Read-only operations are unscoped; write operations require explicit allow-list.
                        2026-06

                        mcp-server-github
                        GitHub REST and search APIs (issues, PRs, code search, branches).
                        Requires a personal access token with appropriate scopes.
                        2026-06

                        mcp-server-postgres
                        PostgreSQL query interface (schema introspection, parameterized queries).
                        Connection string is server-side; client sees only the query API surface.
                        2026-06

                        mcp-server-sqlite
                        SQLite query interface for local .db files.
                        Often used for analytics over exported data.
                        2026-06

                        mcp-server-slack
                        Slack workspace exposure (channels, messages, search).
                        Requires a Slack bot token; channel scopes are token-controlled.
                        2026-06

                        mcp-server-puppeteer
                        Headless browser automation (navigate, click, screenshot, evaluate JS).
                        Side-effect surface is large; the chapter's confirmation-gate discipline applies hard here.
                        2026-06

### How to read this catalog

Two distinctions to keep clean:

- Client vs server - an MCP client is the AI-facing surface (Claude Desktop, Zed, Windsurf, Cursor); an MCP server is the capability the client connects to. Some products are both (a Zed editor is a client, but ships server-side hooks for its own state).

- Spec-listed vs community - the [official servers repo](https://github.com/modelcontextprotocol/servers) hosts reviewed reference implementations; community indexes (such as the [awesome-mcp-servers](https://github.com/punkpeye/awesome-mcp-servers) list) aggregate broader contributions of variable maturity.

### Verification discipline

Each row is marked with the month it was verified against its upstream source. Quarterly refresh; if a row is older than six months, treat it as a snapshot. Corrections welcome via [the errata page](/errata/).