googleapis/mcp-toolbox · error

no valid commands were built to execute

Error message

no valid commands were built to execute

What it means

Valkey Source.RunCommand splits the requested commands, builds valkey-go arbitrary commands via B().Arbitrary(cmd...).Build(), and refuses to run when the resulting builtCmds slice is empty. Because builtCmds is allocated with len(cmds) entries, this fires only when zero commands were supplied in the first place — i.e. the tool invocation carried no command arguments.

Source

Thrown at internal/sources/valkey/valkey.go:142

func (s *Source) ToConfig() sources.SourceConfig {
	return s.Config
}

func (s *Source) ValkeyClient() valkey.Client {
	return s.Client
}

func (s *Source) RunCommand(ctx context.Context, cmds [][]string) (any, error) {
	// Build commands
	builtCmds := make(valkey.Commands, len(cmds))

	for i, cmd := range cmds {
		builtCmds[i] = s.ValkeyClient().B().Arbitrary(cmd...).Build()
	}

	if len(builtCmds) == 0 {
		return nil, fmt.Errorf("no valid commands were built to execute")
	}

	// Execute commands
	responses := s.ValkeyClient().DoMulti(ctx, builtCmds...)

	// Parse responses
	out := make([]any, len(cmds))
	for i, resp := range responses {
		if err := resp.Error(); err != nil {
			// Store error message in the output for this command
			out[i] = fmt.Sprintf("error from executing command at index %d: %s", i, err)
			continue
		}
		val, err := resp.ToAny()
		if err != nil {
			out[i] = fmt.Sprintf("error parsing response: %s", err)
			continue
		}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Pass at least one command in the 'commands' parameter, e.g. ["PING"] or ["GET", "mykey"]
2. Ensure each command is provided as an array of argument strings (['SET','key','value']), not a single joined string
3. Validate client-side that the commands array is non-empty before invoking the tool

Example fix

// before (tool request)
{"commands": []}
// after
{"commands": [["PING"]]}

function validateCommands(cmds: unknown): asserts cmds is string[][] {
  if (!Array.isArray(cmds) || cmds.length === 0)
    throw new Error("'commands' must be a non-empty array of argument arrays");
  if (!cmds.every(c => Array.isArray(c) && c.every(a => typeof a === "string")))
    throw new Error("each command must be an array of strings");
}

function isNonEmptyCommandList(v: unknown): v is string[][] {
  return Array.isArray(v) && v.length > 0 &&
    v.every(c => Array.isArray(c) && c.length > 0 && c.every(a => typeof a === "string"));
}

try {
  const res = await runValkeyCommand(commands);
} catch (err) {
  if (String(err).includes("no valid commands were built")) {
    console.error("commands parameter was empty; send e.g. [[\"PING\"]]");
  }
  throw err;
}

When it happens

Trigger: Calling RunCommand (via the valkey-run-command tool) with an empty commands list: the tool parameters array is missing, empty, or the invoking agent passed an empty array.

Common situations: An LLM agent invoking the run_command tool without filling the commands parameter; a client sending an empty JSON array for commands; misconfigured tool parameter defaults.

Related errors

• error initializing Valkey client: %s
• resources cannot be empty
• description is required for tool %q
• description is required for tool %q
• HTTP error! status: ${response.status}

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/04b365c5189cec01. Report an issue: GitHub.