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Completions

Completions provide real-time autocomplete suggestions for tool parameters. Instead of memorizing project IDs, branch names, or user logins, you type a few characters and the server queries GitLab for matches.

The problem

Section titled “The problem”
Without completions:
  User: "Create issue in project..." → What's the ID? → Must call list_projects first


With completions:
  User types: "mcp" → Server suggests: "group/gitlab-mcp-server", "group/redmine-mcp-server"

This transforms a multi-step lookup into a single, interactive selection.

How it works

Section titled “How it works”
sequenceDiagram
    participant U as User
    participant AI as AI Assistant
    participant S as MCP Server
    participant GL as GitLab API

    U->>AI: Starts typing argument value
    AI->>S: completion/complete (arg: "project_id", value: "mcp")
    S->>GL: GET /projects?search=mcp
    GL-->>S: Matching projects
    S-->>AI: Completion suggestions
    AI->>U: Shows dropdown with options

Supported argument types

Section titled “Supported argument types”

The server supports 17 completion argument types organized into global and per-project completers:

Global completers

Section titled “Global completers”

These work without a project context:

| Argument | Completes | Example | | ----------- | --------------------------- | --------------------- | | project | Project names/paths | my-group/my-project | | group | Group names/paths | engineering | | user | User names/logins | john.doe | | namespace | Namespaces (groups + users) | my-group |

Per-project completers

Section titled “Per-project completers”

These require a project context and search within that project:

| Argument | Completes | Example | | --------------- | --------------------- | ----------------- | | branch | Branch names | feature/login | | tag | Tag names | v1.2.0 | | milestone | Milestone titles | Sprint 14 | | label | Label names | priority::high | | merge_request | MR IIDs | 42 | | issue | Issue IIDs | 100 | | pipeline | Pipeline IDs | 12345 | | environment | Environment names | production | | release | Release tag names | v2.0.0 | | wiki_slug | Wiki page slugs | getting-started | | version | Version/milestone IDs | v1.0 | | runner | Runner descriptions | shared-runner-1 | | board | Board names | Development |

How completions improve AI accuracy

Section titled “How completions improve AI accuracy”

Completions reduce errors in several ways:

  1. Eliminates typos — Users select from validated suggestions instead of typing exact values
  2. Reduces round-trips — No need to call list_projects before create_issue
  3. Provides context — Suggestions include IDs alongside names, ensuring correct values
  4. Real-time search — Results update as the user types, powered by GitLab’s search API