Tools

Every data tool takes an optional project (a project UUID) and an optional env, plus service / key where applicable. When project is omitted it is resolved from .nexus-mcp.json (or the home registry); when env is omitted the backend uses your personal dev environment. Read tools are annotated readOnlyHint; reveal and write tools are annotated destructiveHint, so the host client asks you to confirm before running them.

Authentication tools

Tool	Description
`nexus_login()`	Sign in via the browser (Keycloak device flow). Returns a verification URL + code; once approved, an MCP key is minted and stored on this machine.
`nexus_logout()`	Remove the stored MCP key from this machine. To revoke it server-side, delete it on your profile page.

Discovery

Tool	Description
`list_projects()`	List every project you can access via MCP (across all tenants), each with its `project_id` (UUID) and your `personal_env`. Use a `project_id` in `.nexus-mcp.json` or as the `project` argument.

Read tools

Tool	Description
`list_services(project?, env?)`	List the services in an environment.
`list_configs(project?, env?, service)`	List config entries (values in the friendly `{{secret:KEY}}` / `{{flag:KEY}}` reference form).
`get_config(project?, env?, service, key)`	Get a single config entry.
`list_flags(project?, env?, service)`	List feature flags for a service.
`get_flag(project?, env?, service, key)`	Get a single feature flag.
`list_secrets(project?, env?, service)`	List secret metadata only - never cleartext values.

Reveal and write tools

Tool	Description
`get_secret(project?, env?, service, key, confirm?, key_echo?)`	Metadata by default. To reveal the cleartext value, pass `confirm: true` and `key_echo` equal to the key name. Always rejected in production and unless your grant allows reveal.
`set_config(project?, env?, service, key, value, description?)`	Create or update a config (`value` is any JSON). Creating a new key needs your grant’s create permission, updating an existing one needs write. Always rejected in production.
`delete_config(project?, env?, service, key, confirm)`	Delete a config; requires `confirm: true`. Only allowed in your personal dev environment - rejected on shared envs and in production.
`set_flag(project?, env?, service, key, is_enabled, name?, description?)`	Create or update a feature flag (name / description / enabled only). Create needs create permission, update needs write. Scheduling, rollout %, and targeting are preserved untouched - those stay admin-UI only. Always rejected in production.
`delete_flag(project?, env?, service, key, confirm)`	Delete a feature flag; requires `confirm: true`. Only allowed in your personal dev environment - rejected on shared envs and in production.
`set_secret(project?, env?, service, key, value, type?, description?)`	Create or update a secret value (new version). Create needs create permission, update needs write. Always rejected in production.
`delete_secret(project?, env?, service, key, confirm)`	Delete a secret; requires `confirm: true`. Only allowed in your personal dev environment - rejected on shared envs and in production.

Error messages

Backend errors are translated to clear, actionable messages, for example:

mcp_project_required -> “No project specified. Pass project:<uuid>, add a .nexus-mcp.json, or run list_projects.”
mcp_not_member -> “You are not a member of that project.”
mcp_env_not_allowed -> “That environment is not in your MCP scope (baseline personal env, or your grant).”
mcp_reveal_prod_forbidden -> “Revealing secrets in production is never permitted.”
mcp_write_not_allowed -> “Writing is not permitted by your MCP grant (this grant is read-only).”
mcp_create_not_allowed -> “Creating new items is not permitted by your MCP grant.”
mcp_delete_not_allowed -> “Delete is only allowed in your personal dev env, not on shared environments.”

All enforcement happens on the backend; the server only forwards your call and translates the result.

Getting started

How-to guides

Concepts

AI MCP Server

Beta

Authentication tools

Discovery

Read tools

Reveal and write tools

Error messages

​Authentication tools

​Discovery

​Read tools

​Reveal and write tools

​Error messages

Authentication tools

Discovery

Read tools

Reveal and write tools

Error messages