# MCP

> Add, inspect, or authenticate an MCP server. Use when the user pastes an MCP URL or npx package, says tools are missing, or asks to connect DeepWiki, Playwright, or similar. Not for writing a new MCP server from scratch.

- Skill: `standardharness/mcp` (Agent Skill)
- Install (CLI): `npx skillmds@latest add standardharness/mcp`
- Raw SKILL.md: https://api.skillmd.com/api/skills/standardharness/mcp/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: standardharness (https://skillmd.com/u/standardharness)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/standardharness/mcp

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# MCP

MCP is a host talking to local stdio servers or remote Streamable HTTP servers.
Adding a server means writing a `mcpServers` entry. Do not print env values or
auth headers.

## Classify

- Remote: a `https://…/mcp` URL. Prefer `/mcp` over legacy `/sse`.
- Local: a `command` plus `args` (`npx -y @playwright/mcp`).

Name the server short, lowercase, no spaces. Infer from the URL or package
when the user did not pick one.

## Persist

Prefer the **project** `.mcp.json` unless the user said every project.

```json
{
  "mcpServers": {
    "playwright": { "command": "npx", "args": ["-y", "@playwright/mcp"] },
    "docs": { "url": "https://example.invalid/mcp" }
  }
}
```

If a CLI exists (`graff mcp add`, or the host's equivalent), use it. Merge;
do not drop other servers. Do not commit secrets. OAuth stays the host's login
command.

## Check

After writing, list tools or reconnect. If nothing appears, the command failed
or the URL is wrong — do not invent a parallel config file.