Allow selecting fields in pull request file responses

README.md

@@ -1267,6 +1267,7 @@ The following sets of tools are available:
 - **pull_request_read** - Get details for a single pull request
   - **OAuth Challenge Scopes**: `repo`
   - `after`: Cursor for pagination, used only by the get_review_comments method. Pass the endCursor from the previous page's PageInfo to fetch the next page. (string, optional)
+  - `fields`: Fields to return for each changed file. Only applies when method is 'get_files'. When a nonempty list is provided, only the listed fields are returned. If 'fields' is omitted or empty, all available fields are returned, including patches. (string[], optional)
   - `method`: Action to specify what pull request data needs to be retrieved from GitHub. 
     Possible options: 
      1. get - Get details of a specific pull request.

pkg/github/__toolsnaps__/pull_request_read.snap

@@ -11,6 +11,22 @@
         "description": "Cursor for pagination, used only by the get_review_comments method. Pass the endCursor from the previous page's PageInfo to fetch the next page.",
         "type": "string"
       },
+      "fields": {
+        "description": "Fields to return for each changed file. Only applies when method is 'get_files'. When a nonempty list is provided, only the listed fields are returned. If 'fields' is omitted or empty, all available fields are returned, including patches.",
+        "items": {
+          "enum": [
+            "filename",
+            "status",
+            "additions",
+            "deletions",
+            "changes",
+            "patch",
+            "previous_filename"
+          ],
+          "type": "string"
+        },
+        "type": "array"
+      },
       "method": {
         "description": "Action to specify what pull request data needs to be retrieved from GitHub. \nPossible options: \n 1. get - Get details of a specific pull request.\n 2. get_diff - Get the diff of a pull request.\n 3. get_status - Get combined commit status of a head commit in a pull request.\n 4. get_files - Get the list of files changed in a pull request. Use with pagination parameters to control the number of results returned.\n 5. get_commits - Get the list of commits on a pull request. Use with pagination parameters to control the number of results returned.\n 6. get_review_comments - Get review threads on a pull request. Each thread contains logically grouped review comments made on the same code location during pull request reviews. Returns thread metadata and comments with nullable current and original line-range coordinates (line, start_line, original_line, original_start_line). Current coordinates are omitted when unavailable, such as for outdated comments. Use cursor-based pagination (perPage, after) to control results.\n 7. get_reviews - Get the reviews on a pull request. When asked for review comments, use get_review_comments method. Use with pagination parameters to control the number of results returned.\n 8. get_comments - Get comments on a pull request. Use this if user doesn't specifically want review comments. Use with pagination parameters to control the number of results returned.\n 9. get_check_runs - Get check runs for the head commit of a pull request. Check runs are the individual CI/CD jobs and checks that run on the PR.\n",
         "enum": [

pkg/github/minimal_types.go

@@ -27,6 +27,13 @@ var codeSearchItemFieldEnum = []any{"name", "path", "sha", "repository", "text_m
 // the requested path is a directory; ignored for single files.
 var fileContentFieldEnum = []any{"type", "name", "path", "size", "sha", "url", "git_url", "html_url", "download_url"}
 
+// pullRequestFilesItemFieldEnum lists the selectable fields for pull_request_read
+// get_files results, matching MinimalPRFile. Omitting patch reduces response size
+// when only filenames or file metadata are needed.
+var pullRequestFilesItemFieldEnum = []any{
+	"filename", "status", "additions", "deletions", "changes", "patch", "previous_filename",
+}
+
 // listIssuesItemFieldEnum lists the selectable fields for list_issues result
 // items, matching the JSON field names MinimalIssue actually populates via the
 // list_issues GraphQL fragment (fragmentToMinimalIssue). Fields that only the

pkg/github/pullrequests.go

@@ -59,6 +59,10 @@ Possible options:
 		Required: []string{"method", "owner", "repo", "pullNumber"},
 	}
 	WithPagination(schema)
+	schema.Properties["fields"] = fieldsSchemaProperty(
+		"Fields to return for each changed file. Only applies when method is 'get_files'. When a nonempty list is provided, only the listed fields are returned. If 'fields' is omitted or empty, all available fields are returned, including patches.",
+		pullRequestFilesItemFieldEnum,
+	)
 	// get_review_comments uses GraphQL cursor-based pagination and accepts the
 	// `after` cursor. Other methods rely on the `page`/`perPage` parameters
 	// added by WithPagination and ignore `after`.
@@ -128,7 +132,11 @@ Possible options:
 				result, err := GetPullRequestStatus(ctx, client, owner, repo, pullNumber)
 				return attachIFC(result), nil, err
 			case "get_files":
-				result, err := GetPullRequestFiles(ctx, client, deps, owner, repo, pullNumber, pagination)
+				fields, err := OptionalStringArrayParam(args, "fields")
+				if err != nil {
+					return utils.NewToolResultError(err.Error()), nil, nil
+				}
+				result, err := GetPullRequestFiles(ctx, client, deps, owner, repo, pullNumber, pagination, fields)
 				return attachIFC(result), nil, err
 			case "get_commits":
 				result, err := GetPullRequestCommits(ctx, client, deps, owner, repo, pullNumber, pagination)
@@ -369,7 +377,7 @@ func GetPullRequestCheckRuns(ctx context.Context, client *github.Client, owner,
 	return utils.NewToolResultText(string(r)), nil
 }
 
-func GetPullRequestFiles(ctx context.Context, client *github.Client, deps ToolDependencies, owner, repo string, pullNumber int, pagination PaginationParams) (*mcp.CallToolResult, error) {
+func GetPullRequestFiles(ctx context.Context, client *github.Client, deps ToolDependencies, owner, repo string, pullNumber int, pagination PaginationParams, fields []string) (*mcp.CallToolResult, error) {
 	if restricted, err := enforcePullRequestLockdown(ctx, client, deps, owner, repo, pullNumber); restricted != nil || err != nil {
 		return restricted, err
 	}
@@ -397,6 +405,13 @@ func GetPullRequestFiles(ctx context.Context, client *github.Client, deps ToolDe
 	}
 
 	minimalFiles := convertToMinimalPRFiles(files)
+	if len(fields) > 0 {
+		filteredFiles, err := filterEachField(minimalFiles, fields)
+		if err != nil {
+			return utils.NewToolResultErrorFromErr("failed to filter pull request files", err), nil
+		}
+		return MarshalledTextResult(filteredFiles), nil
+	}
 
 	return MarshalledTextResult(minimalFiles), nil
 }

pkg/github/pullrequests_test.go

@@ -1371,6 +1371,113 @@ func Test_GetPullRequestFiles(t *testing.T) {
 	}
 }
 
+func Test_GetPullRequestFiles_Fields(t *testing.T) {
+	files := []*github.CommitFile{
+		{
+			Filename:         github.Ptr("new.go"),
+			Status:           github.Ptr("renamed"),
+			Additions:        github.Ptr(2),
+			Deletions:        github.Ptr(1),
+			Changes:          github.Ptr(3),
+			Patch:            github.Ptr("@@ -1 +1,2 @@\n-old\n+new\n+line"),
+			PreviousFilename: github.Ptr("old.go"),
+		},
+		{
+			Filename: github.Ptr("image.png"),
+			Status:   github.Ptr("added"),
+		},
+	}
+	full := `[{"filename":"new.go","status":"renamed","additions":2,"deletions":1,"changes":3,"patch":"@@ -1 +1,2 @@\n-old\n+new\n+line","previous_filename":"old.go"},{"filename":"image.png","status":"added"}]`
+
+	for _, tc := range []struct {
+		name    string
+		fields  any
+		omit    bool
+		empty   bool
+		want    string
+		wantErr string
+	}{
+		{
+			name: "omitted fields preserves patches",
+			omit: true,
+			want: full,
+		},
+		{
+			name:   "empty fields preserves patches",
+			fields: []any{},
+			want:   full,
+		},
+		{
+			name:   "filenames only",
+			fields: []any{"filename"},
+			want:   `[{"filename":"new.go"},{"filename":"image.png"}]`,
+		},
+		{
+			name:   "metadata without patches",
+			fields: []any{"filename", "status", "changes", "previous_filename"},
+			want:   `[{"filename":"new.go","status":"renamed","changes":3,"previous_filename":"old.go"},{"filename":"image.png","status":"added"}]`,
+		},
+		{
+			name:   "explicit patch with absent patch omitted",
+			fields: []any{"filename", "patch"},
+			want:   `[{"filename":"new.go","patch":"@@ -1 +1,2 @@\n-old\n+new\n+line"},{"filename":"image.png"}]`,
+		},
+		{
+			name:   "empty results",
+			fields: []any{"filename"},
+			empty:  true,
+			want:   `[]`,
+		},
+		{
+			name:    "invalid fields type",
+			fields:  "filename",
+			wantErr: "fields",
+		},
+		{
+			name:    "invalid field element",
+			fields:  []any{42},
+			wantErr: "fields",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			response := files
+			if tc.empty {
+				response = []*github.CommitFile{}
+			}
+			client := mustNewGHClient(t, MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+				GetReposPullsFilesByOwnerByRepoByPullNumber: func(w http.ResponseWriter, r *http.Request) {
+					require.Empty(t, tc.wantErr, "invalid fields must be rejected before fetching files")
+					expectQueryParams(t, map[string]string{"page": "2", "per_page": "10"}).andThen(mockResponse(t, http.StatusOK, response))(w, r)
+				},
+			}))
+			deps := BaseDeps{Client: client}
+			args := map[string]any{
+				"method":     "get_files",
+				"owner":      "owner",
+				"repo":       "repo",
+				"pullNumber": float64(42),
+				"page":       float64(2),
+				"perPage":    float64(10),
+			}
+			if !tc.omit {
+				args["fields"] = tc.fields
+			}
+			request := createMCPRequest(args)
+			tool := PullRequestRead(translations.NullTranslationHelper)
+			handler := tool.Handler(deps)
+			result, err := handler(ContextWithDeps(context.Background(), deps), &request)
+			require.NoError(t, err)
+			if tc.wantErr != "" {
+				require.True(t, result.IsError)
+				assert.Contains(t, getErrorResult(t, result).Text, tc.wantErr)
+				return
+			}
+			require.False(t, result.IsError)
+			assert.JSONEq(t, tc.want, getTextResult(t, result).Text)
+		})
+	}
+}
+
 func Test_GetPullRequestCommits(t *testing.T) {
 	// Verify tool definition once
 	serverTool := PullRequestRead(translations.NullTranslationHelper)