Add support for retrieving GitHub Issue Comments (github#106)

* Add support for retrieving GitHub Issue Comments

Add new tool 'get_issue_comments' that allows fetching comments associated
with GitHub issues. This complements the existing issue retrieval functionality
and follows the same patterns as the pull request comments implementation.

The implementation includes:
- New getIssueComments function in pkg/github/issues.go
- Tool registration in server.go
- Comprehensive test coverage in issues_test.go

* Support pagination for get_issue_comments

---------

Co-authored-by: Javier Uruen Val <[email protected]>

Author: almostwhitehat

README.md

@@ -153,6 +153,12 @@ export GITHUB_MCP_TOOL_ADD_ISSUE_COMMENT_DESCRIPTION="an alternative description
   - `repo`: Repository name (string, required)
   - `issue_number`: Issue number (number, required)
 
+- **get_issue_comments** - Get comments for a GitHub issue
+
+  - `owner`: Repository owner (string, required)
+  - `repo`: Repository name (string, required)
+  - `issue_number`: Issue number (number, required)
+
 - **create_issue** - Create a new issue in a GitHub repository
 
   - `owner`: Repository owner (string, required)

cmd/mcpcurl/README.md

@@ -50,6 +50,7 @@ Available Commands:
   fork_repository       Fork a GitHub repository to your account or specified organization
   get_file_contents     Get the contents of a file or directory from a GitHub repository
   get_issue             Get details of a specific issue in a GitHub repository.
+  get_issue_comments    Get comments for a GitHub issue
   list_commits          Get list of commits of a branch in a GitHub repository
   list_issues           List issues in a GitHub repository with filtering options
   push_files            Push multiple files to a GitHub repository in a single commit

pkg/github/issues.go

@@ -597,6 +597,81 @@ func updateIssue(client *github.Client, t translations.TranslationHelperFunc) (t
 		}
 }
 
+// getIssueComments creates a tool to get comments for a GitHub issue.
+func getIssueComments(client *github.Client, t translations.TranslationHelperFunc) (tool mcp.Tool, handler server.ToolHandlerFunc) {
+	return mcp.NewTool("get_issue_comments",
+			mcp.WithDescription(t("TOOL_GET_ISSUE_COMMENTS_DESCRIPTION", "Get comments for a GitHub issue")),
+			mcp.WithString("owner",
+				mcp.Required(),
+				mcp.Description("Repository owner"),
+			),
+			mcp.WithString("repo",
+				mcp.Required(),
+				mcp.Description("Repository name"),
+			),
+			mcp.WithNumber("issue_number",
+				mcp.Required(),
+				mcp.Description("Issue number"),
+			),
+			mcp.WithNumber("page",
+				mcp.Description("Page number"),
+			),
+			mcp.WithNumber("per_page",
+				mcp.Description("Number of records per page"),
+			),
+		),
+		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
+			}
+			issueNumber, err := requiredInt(request, "issue_number")
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			page, err := optionalIntParamWithDefault(request, "page", 1)
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+			perPage, err := optionalIntParamWithDefault(request, "per_page", 30)
+			if err != nil {
+				return mcp.NewToolResultError(err.Error()), nil
+			}
+
+			opts := &github.IssueListCommentsOptions{
+				ListOptions: github.ListOptions{
+					Page:    page,
+					PerPage: perPage,
+				},
+			}
+
+			comments, resp, err := client.Issues.ListComments(ctx, owner, repo, issueNumber, opts)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get issue comments: %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 issue comments: %s", string(body))), nil
+			}
+
+			r, err := json.Marshal(comments)
+			if err != nil {
+				return nil, fmt.Errorf("failed to marshal response: %w", err)
+			}
+
+			return mcp.NewToolResultText(string(r)), nil
+		}
+}
+
 // parseISOTimestamp parses an ISO 8601 timestamp string into a time.Time object.
 // Returns the parsed time or an error if parsing fails.
 // Example formats supported: "2023-01-15T14:30:00Z", "2023-01-15"

pkg/github/issues_test.go

@@ -984,3 +984,137 @@ func Test_ParseISOTimestamp(t *testing.T) {
 		})
 	}
 }
+
+func Test_GetIssueComments(t *testing.T) {
+	// Verify tool definition once
+	mockClient := github.NewClient(nil)
+	tool, _ := getIssueComments(mockClient, translations.NullTranslationHelper)
+
+	assert.Equal(t, "get_issue_comments", tool.Name)
+	assert.NotEmpty(t, tool.Description)
+	assert.Contains(t, tool.InputSchema.Properties, "owner")
+	assert.Contains(t, tool.InputSchema.Properties, "repo")
+	assert.Contains(t, tool.InputSchema.Properties, "issue_number")
+	assert.Contains(t, tool.InputSchema.Properties, "page")
+	assert.Contains(t, tool.InputSchema.Properties, "per_page")
+	assert.ElementsMatch(t, tool.InputSchema.Required, []string{"owner", "repo", "issue_number"})
+
+	// Setup mock comments for success case
+	mockComments := []*github.IssueComment{
+		{
+			ID:   github.Ptr(int64(123)),
+			Body: github.Ptr("This is the first comment"),
+			User: &github.User{
+				Login: github.Ptr("user1"),
+			},
+			CreatedAt: &github.Timestamp{Time: time.Now().Add(-time.Hour * 24)},
+		},
+		{
+			ID:   github.Ptr(int64(456)),
+			Body: github.Ptr("This is the second comment"),
+			User: &github.User{
+				Login: github.Ptr("user2"),
+			},
+			CreatedAt: &github.Timestamp{Time: time.Now().Add(-time.Hour)},
+		},
+	}
+
+	tests := []struct {
+		name             string
+		mockedClient     *http.Client
+		requestArgs      map[string]interface{}
+		expectError      bool
+		expectedComments []*github.IssueComment
+		expectedErrMsg   string
+	}{
+		{
+			name: "successful comments retrieval",
+			mockedClient: mock.NewMockedHTTPClient(
+				mock.WithRequestMatch(
+					mock.GetReposIssuesCommentsByOwnerByRepoByIssueNumber,
+					mockComments,
+				),
+			),
+			requestArgs: map[string]interface{}{
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+			},
+			expectError:      false,
+			expectedComments: mockComments,
+		},
+		{
+			name: "successful comments retrieval with pagination",
+			mockedClient: mock.NewMockedHTTPClient(
+				mock.WithRequestMatchHandler(
+					mock.GetReposIssuesCommentsByOwnerByRepoByIssueNumber,
+					expectQueryParams(t, map[string]string{
+						"page":     "2",
+						"per_page": "10",
+					}).andThen(
+						mockResponse(t, http.StatusOK, mockComments),
+					),
+				),
+			),
+			requestArgs: map[string]interface{}{
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(42),
+				"page":         float64(2),
+				"per_page":     float64(10),
+			},
+			expectError:      false,
+			expectedComments: mockComments,
+		},
+		{
+			name: "issue not found",
+			mockedClient: mock.NewMockedHTTPClient(
+				mock.WithRequestMatchHandler(
+					mock.GetReposIssuesCommentsByOwnerByRepoByIssueNumber,
+					mockResponse(t, http.StatusNotFound, `{"message": "Issue not found"}`),
+				),
+			),
+			requestArgs: map[string]interface{}{
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(999),
+			},
+			expectError:    true,
+			expectedErrMsg: "failed to get issue comments",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			// Setup client with mock
+			client := github.NewClient(tc.mockedClient)
+			_, handler := getIssueComments(client, translations.NullTranslationHelper)
+
+			// Create call request
+			request := createMCPRequest(tc.requestArgs)
+
+			// Call handler
+			result, err := handler(context.Background(), request)
+
+			// Verify results
+			if tc.expectError {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.expectedErrMsg)
+				return
+			}
+
+			require.NoError(t, err)
+			textContent := getTextResult(t, result)
+
+			// Unmarshal and verify the result
+			var returnedComments []*github.IssueComment
+			err = json.Unmarshal([]byte(textContent.Text), &returnedComments)
+			require.NoError(t, err)
+			assert.Equal(t, len(tc.expectedComments), len(returnedComments))
+			if len(returnedComments) > 0 {
+				assert.Equal(t, *tc.expectedComments[0].Body, *returnedComments[0].Body)
+				assert.Equal(t, *tc.expectedComments[0].User.Login, *returnedComments[0].User.Login)
+			}
+		})
+	}
+}

pkg/github/server.go

@@ -34,6 +34,7 @@ func NewServer(client *github.Client, readOnly bool, t translations.TranslationH
 	s.AddTool(getIssue(client, t))
 	s.AddTool(searchIssues(client, t))
 	s.AddTool(listIssues(client, t))
+	s.AddTool(getIssueComments(client, t))
 	if !readOnly {
 		s.AddTool(createIssue(client, t))
 		s.AddTool(addIssueComment(client, t))