MCP server

gum mcp --stdio runs the MCP server. The public release supports stdio transport.

bash

gum mcp --stdio

Most users should let gum setup write client config instead of editing MCP files by hand:

bash

gum setup --dry-run
gum setup --target codex --features skills,mcp --yes

Tool shape

The MCP surface starts small. Core meta-tools search, describe, and invoke the catalog, while convenience tools cover common Gmail, Drive, Calendar, Docs, Sheets, Slides, Tasks, and Flights paths.

The stable path for long-tail API access is:

text

gum.search_apis -> gum.describe_op -> gum.read / gum.write / gum.destructive

The CLI mirrors the same model with gum search, gum describe, gum read, gum write, and gum destructive.

Meta-tool tuning

gum.search_apis and gum.describe_op shape their own output. Five per-profile config keys move the limits:

Key	Default	Effect
`meta_tools.search_apis.k`	5	Result count when the caller sends no `k`. Range 1-20.
`meta_tools.search_apis.truncate_strings.default_chars`	120	Character limit on summary-class fields in a result row. Range 60-400.
`meta_tools.search_apis.collapse_arrays.max_items`	binds `k`	Collapse threshold for the results array. Range 1-50.
`meta_tools.describe_op.max_variants`	5	Collapse threshold for the `variants[]` array. Range 1-50.
`meta_tools.describe_op.max_chars`	400	Character limit on `gum.describe_op` string fields. Range 100-2000.

bash

gum config set meta_tools.describe_op.max_chars=1200

A value outside its range is clamped and logged; an unparseable value falls back to the default. These keys do not rebind an expression profile and do not change the registered tool schemas.

Safety boundary

MCP clients do not receive raw Google tokens. They call the local gum server, and gum resolves credentials from the selected profile on that host. Writes and destructive calls still pass through the same risk gate as CLI calls.

Use Safety before exposing gum to unattended agents.