Terraform MCP Server

What it does

HashiCorp's own MCP server for Terraform does two separate jobs. The first is looking things up in the public Terraform Registry: searching provider documentation, modules and Sentinel/OPA policies, fetching the docs for a given resource or data source, and finding the newest version of a provider or module. Run locally, this part needs no account.

The second job is working on an HCP Terraform or Terraform Enterprise organization. With an API token it can list organizations and projects, create and update workspaces, set workspace variables and variable sets, tag workspaces, attach policy sets, manage teams, start runs, and read plan and apply logs, structured plan JSON, state versions and Stacks. It can also search an organization's private registry. The tools that delete projects, teams or workspaces, force-unlock a workspace or act on runs are not registered at all unless ENABLE_TF_OPERATIONS is true (pkg/tools/dynamic_tool.go), and create_run only offers auto-approve and destroy runs then.

Version 1.4.1 registers 61 tools (pkg/toolsets/registry.go). Tools are grouped into the toolsets registry, registry-private and terraform. The README says only registry is on by default, but in the 1.4.1 code the --toolsets flag defaults to all (pkg/cli/commands.go). The token-based tools are simply not registered until a session has a working HCP Terraform client. --tools narrows it to single tools. It also serves read-only resources such as the Terraform style guide. It runs over stdio for one user or as a Streamable HTTP service that several users share, each sending their own token.

HashiCorp also runs it for you at mcp.terraform.io, currently in beta. That copy talks to HCP Terraform only, so Terraform Enterprise users still need to run their own. It asks for a token even for plain registry lookups. You can't change its settings, and the five destructive tools are left out, which also means create_run can't do auto-approve or destroy runs there.

What it needs

Docker for the published image, or a Go toolchain to build it with go install. Registry lookups need nothing else. The HCP Terraform and private registry tools need an API token in TFE_TOKEN, plus TFE_ADDRESS when the instance is not app.terraform.io.

Limits

• Not covered Talks to the Terraform Registry and, with a valid TFE_TOKEN, the HCP Terraform/TFE APIs. It does not run the terraform CLI against local files or state
• Read only Deletes, force-unlock, run actions and auto-approve or destroy runs are unavailable unless ENABLE_TF_OPERATIONS=true, and never on the hosted endpoint
• Early release The hosted endpoint at mcp.terraform.io is in beta, and HashiCorp advises against relying on it in production
• Not covered The hosted endpoint reaches HCP Terraform only, needs a token even for registry tools, and its toolsets and settings cannot be changed
• Limit Its README says only the registry toolset is on by default, but the 1.4.1 code enables all toolsets when --toolsets is not given
• Limit The Search toolset (execute_query, prepare_import and related tools) and its TF_MCP_QUERY_WORKSPACE, TF_CLOUD_ORGANIZATION settings are only on main, not released
• Limit Setting TRANSPORT_PORT, TRANSPORT_HOST or MCP_ENDPOINT alone switches it to HTTP mode instead of stdio (pkg/cli/flags.go)
• Rate limit HTTP mode rate-limits to 10 requests/s (burst 20) globally and 5/s (burst 10) per session by default. The hosted endpoint returns a tool error, not HTTP 429, when over
• Limit In HTTP mode it refuses to bind to a non-localhost address without MCP_TLS_CERT_FILE and MCP_TLS_KEY_FILE
• Limit Its makers warn that its output must be reviewed before acting on it

The README says only the registry toolset is on by default, yet in the released code every toolset is enabled when --toolsets is not passed. The private registry and HCP Terraform tools still appear only once a valid token is set. Deleting projects, teams and workspaces, force-unlocking workspaces, acting on runs, and auto-approve or destroy runs are refused unless ENABLE_TF_OPERATIONS=true. In HTTP mode TFE_ADDRESS can only be set on the server, and tokens in query strings are rejected.

Who it suits

Suits anyone writing Terraform who wants provider and module details looked up from the registry, and teams on HCP Terraform or Terraform Enterprise who want an assistant to inspect workspaces and runs or set up workspaces and variables. HCP Terraform users who would rather not run Docker can point a client at the hosted beta endpoint with a token. Terraform Enterprise users, and anyone who needs the delete or run-action tools, have to run it themselves. Platform teams can self-host one shared HTTP instance with per-user tokens and an organization allowlist. To keep an assistant from changing your organization, pass --toolsets=registry or leave ENABLE_TF_OPERATIONS false.