charmbracelet/crush · error

session ID is required for listing MCP resources

Error message

session ID is required for listing MCP resources

What it means

The list_mcp_resources tool needs a session ID to associate the permission request with a conversation. GetSessionFromContext returns empty when the tool runs outside an agent session, so the tool aborts with this error instead of requesting permissions it cannot attribute.

Source

Thrown at internal/agent/tools/list_mcp_resources.go:43

const ListMCPResourcesToolName = "list_mcp_resources"

//go:embed list_mcp_resources.md
var listMCPResourcesDescription string

func NewListMCPResourcesTool(cfg *config.ConfigStore, permissions permission.Service) fantasy.AgentTool {
	return fantasy.NewParallelAgentTool(
		ListMCPResourcesToolName,
		listMCPResourcesDescription,
		func(ctx context.Context, params ListMCPResourcesParams, call fantasy.ToolCall) (fantasy.ToolResponse, error) {
			params.MCPName = strings.TrimSpace(params.MCPName)
			if params.MCPName == "" {
				return fantasy.NewTextErrorResponse("mcp_name parameter is required"), nil
			}

			sessionID := GetSessionFromContext(ctx)
			if sessionID == "" {
				return fantasy.ToolResponse{}, fmt.Errorf("session ID is required for listing MCP resources")
			}

			relPath := filepathext.SmartJoin(cfg.WorkingDir(), params.MCPName)
			p, err := permissions.Request(
				ctx,
				permission.CreatePermissionRequest{
					SessionID:   sessionID,
					Path:        relPath,
					ToolCallID:  call.ID,
					ToolName:    ListMCPResourcesToolName,
					Action:      "list",
					Description: fmt.Sprintf("List MCP resources from %s", params.MCPName),
					Params:      ListMCPResourcesPermissionsParams(params),
				},
			)
			if err != nil {
				return fantasy.ToolResponse{}, err
			}

View on GitHub (pinned to 7944b8e522)

Solutions

1. Ensure the tool is executed through the normal agent pipeline, which injects the session ID into the context.
2. In tests, set the session ID explicitly via the context helper (GetSessionFromContext counterpart) before invoking the tool.
3. If embedding the tool elsewhere, attach a valid session ID to the context first.

Example fix

// before
resp, _ := tool.Execute(ctx, params) // ctx has no session
// after
ctx = WithSession(ctx, sessionID)
resp, _ := tool.Execute(ctx, params)

if GetSessionFromContext(ctx) == "" {
    return errors.New("cannot list MCP resources without a session")
}

null

if err := run(); err != nil {
    if strings.Contains(err.Error(), "session ID is required") { /* attach session and retry */ }
}

When it happens

Trigger: Invoking the ListMcpResources tool (with mcp_name set) from a context that lacks a session, e.g. calling the tool's Execute function directly in tests or from a non-session code path.

Common situations: Unit tests calling the tool handler without seeding the context, MCP resource listing attempted during startup or from background jobs that bypass the agent session.

Related errors

• session ID is required for executing shell command
• session ID is required for downloading files
• session ID is required for creating a new file
• session ID is required for accessing directories outside wor
• session ID is required for creating a new file

AI-assisted analysis of charmbracelet/crush@7944b8e522 (2026-08-29). Data as JSON: /api/errors/fe9b78ff5fc39dfc. Report an issue: GitHub.