Add custom_instructions parameter to assign_copilot_to_issue tool

- Added optional custom_instructions parameter to tool schema
- Updated implementation to pass custom instructions to agent assignment
- Added test case to verify custom_instructions works correctly
- Updated toolsnaps and documentation

The custom_instructions parameter allows users to provide additional
context, constraints, or guidance to the Copilot agent beyond what's
in the issue body, addressing the issue where additional context
would otherwise be lost.

Co-authored-by: SamMorrowDrums <4811358+SamMorrowDrums@users.noreply.github.com>

Author: Copilot

README.md

@@ -752,6 +752,7 @@ The following sets of tools are available:
 - **assign_copilot_to_issue** - Assign Copilot to issue
   - **Required OAuth Scopes**: `repo`
   - `base_ref`: Git reference (e.g., branch) that the agent will start its work from. If not specified, defaults to the repository's default branch (string, optional)
+  - `custom_instructions`: Optional custom instructions to guide the agent beyond the issue body. Use this to provide additional context, constraints, or guidance that is not captured in the issue description (string, optional)
   - `issue_number`: Issue number (number, required)
   - `owner`: Repository owner (string, required)
   - `repo`: Repository name (string, required)

pkg/github/__toolsnaps__/assign_copilot_to_issue.snap

@@ -22,6 +22,10 @@
         "description": "Git reference (e.g., branch) that the agent will start its work from. If not specified, defaults to the repository's default branch",
         "type": "string"
       },
+      "custom_instructions": {
+        "type": "string",
+        "description": "Optional custom instructions to guide the agent beyond the issue body. Use this to provide additional context, constraints, or guidance that is not captured in the issue description"
+      },
       "issue_number": {
         "description": "Issue number",
         "type": "number"

pkg/github/issues.go

@@ -1650,17 +1650,22 @@ func AssignCopilotToIssue(t translations.TranslationHelperFunc) inventory.Server
 						Type:        "string",
 						Description: "Git reference (e.g., branch) that the agent will start its work from. If not specified, defaults to the repository's default branch",
 					},
+					"custom_instructions": {
+						Type:        "string",
+						Description: "Optional custom instructions to guide the agent beyond the issue body. Use this to provide additional context, constraints, or guidance that is not captured in the issue description",
+					},
 				},
 				Required: []string{"owner", "repo", "issue_number"},
 			},
 		},
 		[]scopes.Scope{scopes.Repo},
 		func(ctx context.Context, deps ToolDependencies, _ *mcp.CallToolRequest, args map[string]any) (*mcp.CallToolResult, any, error) {
 			var params struct {
-				Owner       string `mapstructure:"owner"`
-				Repo        string `mapstructure:"repo"`
-				IssueNumber int32  `mapstructure:"issue_number"`
-				BaseRef     string `mapstructure:"base_ref"`
+				Owner              string `mapstructure:"owner"`
+				Repo               string `mapstructure:"repo"`
+				IssueNumber        int32  `mapstructure:"issue_number"`
+				BaseRef            string `mapstructure:"base_ref"`
+				CustomInstructions string `mapstructure:"custom_instructions"`
 			}
 			if err := mapstructure.Decode(args, &params); err != nil {
 				return utils.NewToolResultError(err.Error()), nil, nil
@@ -1775,6 +1780,12 @@ func AssignCopilotToIssue(t translations.TranslationHelperFunc) inventory.Server
 				agentAssignment.BaseRef = &baseRef
 			}
 
+			// Add custom instructions if provided
+			if params.CustomInstructions != "" {
+				customInstructions := githubv4.String(params.CustomInstructions)
+				agentAssignment.CustomInstructions = &customInstructions
+			}
+
 			// Execute the updateIssue mutation with the GraphQL-Features header
 			// This header is required for the agent assignment API which is not GA yet
 			var updateIssueMutation struct {

pkg/github/issues_test.go

@@ -2086,6 +2086,7 @@ func TestAssignCopilotToIssue(t *testing.T) {
 	assert.Contains(t, tool.InputSchema.(*jsonschema.Schema).Properties, "repo")
 	assert.Contains(t, tool.InputSchema.(*jsonschema.Schema).Properties, "issue_number")
 	assert.Contains(t, tool.InputSchema.(*jsonschema.Schema).Properties, "base_ref")
+	assert.Contains(t, tool.InputSchema.(*jsonschema.Schema).Properties, "custom_instructions")
 	assert.ElementsMatch(t, tool.InputSchema.(*jsonschema.Schema).Required, []string{"owner", "repo", "issue_number"})
 
 	// Helper function to create pointer to githubv4.String
@@ -2638,6 +2639,116 @@ func TestAssignCopilotToIssue(t *testing.T) {
 				),
 			),
 		},
+		{
+			name: "successful assignment with custom_instructions specified",
+			requestArgs: map[string]any{
+				"owner":               "owner",
+				"repo":                "repo",
+				"issue_number":        float64(123),
+				"custom_instructions": "Please ensure all code follows PEP 8 style guidelines and includes comprehensive docstrings",
+			},
+			mockedClient: githubv4mock.NewMockedHTTPClient(
+				githubv4mock.NewQueryMatcher(
+					struct {
+						Repository struct {
+							SuggestedActors struct {
+								Nodes []struct {
+									Bot struct {
+										ID       githubv4.ID
+										Login    githubv4.String
+										TypeName string `graphql:"__typename"`
+									} `graphql:"... on Bot"`
+								}
+								PageInfo struct {
+									HasNextPage bool
+									EndCursor   string
+								}
+							} `graphql:"suggestedActors(first: 100, after: $endCursor, capabilities: CAN_BE_ASSIGNED)"`
+						} `graphql:"repository(owner: $owner, name: $name)"`
+					}{},
+					map[string]any{
+						"owner":     githubv4.String("owner"),
+						"name":      githubv4.String("repo"),
+						"endCursor": (*githubv4.String)(nil),
+					},
+					githubv4mock.DataResponse(map[string]any{
+						"repository": map[string]any{
+							"suggestedActors": map[string]any{
+								"nodes": []any{
+									map[string]any{
+										"id":         githubv4.ID("copilot-swe-agent-id"),
+										"login":      githubv4.String("copilot-swe-agent"),
+										"__typename": "Bot",
+									},
+								},
+							},
+						},
+					}),
+				),
+				githubv4mock.NewQueryMatcher(
+					struct {
+						Repository struct {
+							ID    githubv4.ID
+							Issue struct {
+								ID        githubv4.ID
+								Assignees struct {
+									Nodes []struct {
+										ID githubv4.ID
+									}
+								} `graphql:"assignees(first: 100)"`
+							} `graphql:"issue(number: $number)"`
+						} `graphql:"repository(owner: $owner, name: $name)"`
+					}{},
+					map[string]any{
+						"owner":  githubv4.String("owner"),
+						"name":   githubv4.String("repo"),
+						"number": githubv4.Int(123),
+					},
+					githubv4mock.DataResponse(map[string]any{
+						"repository": map[string]any{
+							"id": githubv4.ID("test-repo-id"),
+							"issue": map[string]any{
+								"id": githubv4.ID("test-issue-id"),
+								"assignees": map[string]any{
+									"nodes": []any{},
+								},
+							},
+						},
+					}),
+				),
+				githubv4mock.NewMutationMatcher(
+					struct {
+						UpdateIssue struct {
+							Issue struct {
+								ID     githubv4.ID
+								Number githubv4.Int
+								URL    githubv4.String
+							}
+						} `graphql:"updateIssue(input: $input)"`
+					}{},
+					UpdateIssueInput{
+						ID:          githubv4.ID("test-issue-id"),
+						AssigneeIDs: []githubv4.ID{githubv4.ID("copilot-swe-agent-id")},
+						AgentAssignment: &AgentAssignmentInput{
+							BaseRef:            nil,
+							CustomAgent:        ptrGitHubv4String(""),
+							CustomInstructions: ptrGitHubv4String("Please ensure all code follows PEP 8 style guidelines and includes comprehensive docstrings"),
+							TargetRepositoryID: githubv4.ID("test-repo-id"),
+						},
+					},
+					nil,
+					githubv4mock.DataResponse(map[string]any{
+						"updateIssue": map[string]any{
+							"issue": map[string]any{
+								"id":     githubv4.ID("test-issue-id"),
+								"number": githubv4.Int(123),
+								"url":    githubv4.String("https://github.com/owner/repo/issues/123"),
+							},
+						},
+					}),
+				),
+			),
+		},
 	}
 
 	for _, tc := range tests {