feat: Add support for git tag operations

Add git tag functionality including:
- List repository tags
- Get tag details
- Support for tag-based content access

This enables basic read-only tag management through the MCP server API.

Author: eranco74

pkg/github/repositories.go

@@ -796,3 +796,147 @@ func PushFiles(getClient GetClientFn, t translations.TranslationHelperFunc) (too
 			return mcp.NewToolResultText(string(r)), nil
 		}
 }
+
+// ListTags creates a tool to list tags in a GitHub repository.
+func ListTags(getClient GetClientFn, t translations.TranslationHelperFunc) (tool mcp.Tool, handler server.ToolHandlerFunc) {
+	return mcp.NewTool("list_tags",
+			mcp.WithDescription(t("TOOL_LIST_TAGS_DESCRIPTION", "List tags in a GitHub repository")),
+			mcp.WithToolAnnotation(mcp.ToolAnnotation{
+				Title:        t("TOOL_LIST_TAGS_USER_TITLE", "List tags"),
+				ReadOnlyHint: true,
+			}),
+			mcp.WithString("owner",
+				mcp.Required(),
+				mcp.Description("Repository owner"),
+			),
+			mcp.WithString("repo",
+				mcp.Required(),
+				mcp.Description("Repository name"),
+			),
+			WithPagination(),
+		),
+		func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+			owner, err := requiredParam[string](request, "owner")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			repo, err := requiredParam[string](request, "repo")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			pagination, err := OptionalPaginationParams(request)
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+
+			opts := &github.ListOptions{
+				Page:    pagination.page,
+				PerPage: pagination.perPage,
+			}
+
+			client, err := getClient(ctx)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get GitHub client: %w", err)
+			}
+
+			tags, resp, err := client.Repositories.ListTags(ctx, owner, repo, opts)
+			if err != nil {
+				return nil, fmt.Errorf("failed to list tags: %w", err)
+			}
+			defer func() { _ = resp.Body.Close() }()
+
+			if resp.StatusCode != http.StatusOK {
+				body, err := io.ReadAll(resp.Body)
+				if err != nil {
+					return nil, fmt.Errorf("failed to read response body: %w", err)
+				}
+				return mcp.NewToolResultError(fmt.Sprintf("failed to list tags: %s", string(body))), nil
+			}
+
+			r, err := json.Marshal(tags)
+			if err != nil {
+				return nil, fmt.Errorf("failed to marshal response: %w", err)
+			}
+
+			return mcp.NewToolResultText(string(r)), nil
+		}
+}
+
+// GetTag creates a tool to get details about a specific tag in a GitHub repository.
+func GetTag(getClient GetClientFn, t translations.TranslationHelperFunc) (tool mcp.Tool, handler server.ToolHandlerFunc) {
+	return mcp.NewTool("get_tag",
+			mcp.WithDescription(t("TOOL_GET_TAG_DESCRIPTION", "Get details about a specific tag in a GitHub repository")),
+			mcp.WithToolAnnotation(mcp.ToolAnnotation{
+				Title:        t("TOOL_GET_TAG_USER_TITLE", "Get tag details"),
+				ReadOnlyHint: true,
+			}),
+			mcp.WithString("owner",
+				mcp.Required(),
+				mcp.Description("Repository owner"),
+			),
+			mcp.WithString("repo",
+				mcp.Required(),
+				mcp.Description("Repository name"),
+			),
+			mcp.WithString("tag",
+				mcp.Required(),
+				mcp.Description("Tag name"),
+			),
+		),
+		func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+			owner, err := requiredParam[string](request, "owner")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			repo, err := requiredParam[string](request, "repo")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			tag, err := requiredParam[string](request, "tag")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+
+			client, err := getClient(ctx)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get GitHub client: %w", err)
+			}
+
+			// First get the tag reference
+			ref, resp, err := client.Git.GetRef(ctx, owner, repo, "refs/tags/"+tag)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get tag reference: %w", err)
+			}
+			defer func() { _ = resp.Body.Close() }()
+
+			if resp.StatusCode != http.StatusOK {
+				body, err := io.ReadAll(resp.Body)
+				if err != nil {
+					return nil, fmt.Errorf("failed to read response body: %w", err)
+				}
+				return mcp.NewToolResultError(fmt.Sprintf("failed to get tag reference: %s", string(body))), nil
+			}
+
+			// Then get the tag object
+			tagObj, resp, err := client.Git.GetTag(ctx, owner, repo, *ref.Object.SHA)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get tag object: %w", err)
+			}
+			defer func() { _ = resp.Body.Close() }()
+
+			if resp.StatusCode != http.StatusOK {
+				body, err := io.ReadAll(resp.Body)
+				if err != nil {
+					return nil, fmt.Errorf("failed to read response body: %w", err)
+				}
+				return mcp.NewToolResultError(fmt.Sprintf("failed to get tag object: %s", string(body))), nil
+			}
+
+			r, err := json.Marshal(tagObj)
+			if err != nil {
+				return nil, fmt.Errorf("failed to marshal response: %w", err)
+			}
+
+			return mcp.NewToolResultText(string(r)), nil
+		}
+}