get_merge_request_diffs

Retrieve code changes from GitLab merge requests to review modifications between branches. Specify project ID with either merge request ID or source branch name.

Instructions

Get the changes/diffs of a merge request. Either merge_request_iid or source_branch must be provided.

Input Schema

TableJSON Schema

Name	Required	Description
`project_id`	Yes	Project ID or path
`merge_request_iid`	No	Merge request internal ID
`source_branch`	No	Source branch name (alternative to merge_request_iid)
`view`	No	Diff view type

Implementation Reference

src/handlers/merge-requests.ts:135-162 (handler)

The core handler function implementing get_merge_request_diffs tool. Resolves merge request IID from source_branch if not provided, constructs the GitLab API URL for MR changes/diffs, fetches the data, and returns it as JSON text content.

async getMergeRequestDiffs(args: GetMergeRequestDiffsParams) {
  const mergeRequestIid = await this.resolveMergeRequestIid(
    args.project_id,
    args.merge_request_iid,
    args.source_branch
  );

  const params = new URLSearchParams();
  if (args.view) params.append("view", args.view);

  const queryString = params.toString();
  const url = `/projects/${encodeURIComponent(
    args.project_id
  )}/merge_requests/${mergeRequestIid}/changes${
    queryString ? `?${queryString}` : ""
  }`;

  const data = await this.client.get(url);

  return {
    content: [
      {
        type: "text",
        text: JSON.stringify(data, null, 2),
      },
    ],
  };
}

src/tools/merge-requests.ts:85-111 (schema)

MCP tool definition including name, description, and inputSchema for the get_merge_request_diffs tool.

{
  name: 'get_merge_request_diffs',
  description: 'Get the changes/diffs of a merge request. Either merge_request_iid or source_branch must be provided.',
  inputSchema: {
    type: 'object',
    properties: {
      project_id: {
        type: 'string',
        description: 'Project ID or path',
      },
      merge_request_iid: {
        type: 'number',
        description: 'Merge request internal ID',
      },
      source_branch: {
        type: 'string',
        description: 'Source branch name (alternative to merge_request_iid)',
      },
      view: {
        type: 'string',
        enum: ['inline', 'parallel'],
        description: 'Diff view type',
      },
    },
    required: ['project_id'],
  },
},

src/server.ts:193-196 (registration)

Server dispatch/registration for the tool call, routing to the mergeRequestHandlers.getMergeRequestDiffs method.

case "get_merge_request_diffs":
  return await this.mergeRequestHandlers.getMergeRequestDiffs(
    args as unknown as GetMergeRequestDiffsParams
  );

src/types.ts:260-265 (schema)

TypeScript interface defining the parameters for the getMergeRequestDiffs handler.

export interface GetMergeRequestDiffsParams {
  project_id: string;
  merge_request_iid?: number;
  source_branch?: string;
  view?: 'inline' | 'parallel';
}

GitLab MCP Server