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mcpdo connection client changeddocs/2026-07-28/tools/inspector/mcpdo

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Upstream edited this page at 8 Oct 2026 12:58 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 22 Oct 2026 20:37 UTC.

Upstream edited 8 Oct 2026 12:58 UTC

Recorded here 22 Oct 2026 20:37 UTC

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33> Connect to an MCP server once, then run many commands against that named connection

5`mcpdo` is an **experimental** command-line client that ships in the `@modelcontextprotocol/inspector` package alongside `mcp-inspector`. Where the [CLI client](/docs/2026-07-28/tools/inspector/cli) connects, runs one `--method` and disconnects, `mcpdo` **connects once** and keeps the connection open, so you can run many commands against it from any shell, the way `ssh-agent` keeps keys loaded.

5`mcpdo` is an **experimental** command-line client that ships in the `@modelcontextprotocol/inspector` package alongside `mcp-inspector`. Where the [CLI client](/docs/2026-07-28/tools/inspector/cli.md) connects, runs one `--method` and disconnects, `mcpdo` **connects once** and keeps the connection open, so you can run many commands against it from any shell, the way `ssh-agent` keeps keys loaded.

77| | `mcp-inspector --cli` | `mcpdo` |

88| - | - | - |

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1010| **State** | None between runs | Named connections held by a daemon |

1111| **Best for** | CI assertions, one JSON blob per run | Exploring a server, agent tool use, multi-step flows over one session (tasks, subscriptions, elicitation) |

1212

13Connections are held by a local background daemon, `mcpdod`, which `mcpdo` starts on demand and stops after its last connection closes. You never start it by hand. What it exposes, and how it is protected, is described under [The mcpdo connection daemon](/docs/2026-07-28/tools/inspector/security#the-mcpdo-connection-daemon).

1414

1515Watch the [mcpdo tutorial video](https://www.youtube.com/watch?v=_a6eG0y156k).

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5151mcpdo connect node build/index.js # ad-hoc stdio server

5252```

5353

54The catalog and `--config` behave exactly as for the other clients (see [Configuration and flags](/docs/2026-07-28/tools/inspector/configuration#choosing-servers)): the default catalog is `~/.mcp-inspector/mcp.json`, overridable with `--catalog` or `MCP_CATALOG_PATH`. `servers/list` and `servers/show <name>` read entries from disk. `connections/*` shows what the daemon currently holds. There are no commands to edit the catalog; edit the file directly.

54The catalog and `--config` behave exactly as for the other clients (see [Configuration and flags](/docs/2026-07-28/tools/inspector/configuration.md#choosing-servers)): the default catalog is `~/.mcp-inspector/mcp.json`, overridable with `--catalog` or `MCP_CATALOG_PATH`. `servers/list` and `servers/show <name>` read entries from disk. `connections/*` shows what the daemon currently holds. There are no commands to edit the catalog; edit the file directly.

5555

5656A stdio server runs with the working directory and command resolution of the shell that ran `connect`, not of the daemon, so relative paths and bare command names mean what you would expect.

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111111

112112When a browser sign-in is needed and neither stdin nor stderr is a TTY (and `MCP_AUTO_OPEN_ENABLED` is not forced on), `connect` exits `0` immediately with `pendingAuth: true` and an `authUrl`. Relay that URL to whoever will sign in. The connection completes on its own once they do: the next real command against it finishes the connection, and `connections/list` reports `pendingAuthSignedIn` in the meantime. Don't reconnect to fix a pending sign-in.

113113

114On a host with no OS keychain, `mcpdo` stores tokens in the shared `secrets.json` file, never in memory, because its commands and the daemon are separate processes. That file is plaintext unless you supply a key; see [Where secrets are stored](/docs/2026-07-28/tools/inspector/configuration#where-secrets-are-stored).

115115

116116## Elicitation

117117

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131131

132132## Protocol eras

133133

134`mcpdo` negotiates the same [protocol eras](/docs/2026-07-28/tools/inspector/protocol-eras) as the other clients. `connect --era legacy|auto|modern` overrides a catalog entry's `protocolEra`, and is the only way to set it for an ad-hoc target. `connections/list` tags each connection `[legacy]` or `[modern]`, and `connections/show <name>` gives the negotiated version, server info, capabilities, and the supported-versions list when the server was probed.

134`mcpdo` negotiates the same [protocol eras](/docs/2026-07-28/tools/inspector/protocol-eras.md) as the other clients. `connect --era legacy|auto|modern` overrides a catalog entry's `protocolEra`, and is the only way to set it for an ad-hoc target. `connections/list` tags each connection `[legacy]` or `[modern]`, and `connections/show <name>` gives the negotiated version, server info, capabilities, and the supported-versions list when the server was probed.

135135

136136## The daemon

137137

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159159

160160## Environment variables

161161

162`mcpdo` reads the same catalog, storage and secret-store variables as the other clients (see [Environment variables](/docs/2026-07-28/tools/inspector/configuration#environment-variables)), plus these:

163163

164164| Variable | Effect |

165165| - | - |