deepseek-ai/deepseek-harness · error

Tool "${rawName}" requires task-based execution, which this

Error message

Tool "${rawName}" requires task-based execution, which this bridge does not support

What it means

Error "Tool "${rawName}" requires task-based execution, which this bridge does not support" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/mcp/mcp-client/src/tools.ts:313

 * raw MCP tool name and sends an uncached `tools/call` request with it (never
 * the public name), with abort signal and timeout, then maps the result to
 * harness ContentBlocks. Owning the raw request prevents the SDK's internal
 * per-page schema cache from pre-validating a different contract.
 *
 * When the MCP server returns `isError: true`, the executor throws so that
 * the ToolRuntime's catch path produces an `isError` result for the model.
 */
function createExecutor(
  client: Client,
  ctx: Context,
  rawName: string,
  taskRequired: boolean,
  opts: ToolBridgeOptions,
  projections: WeakMap<ToolExecution, PreparedProjection>,
): ToolDefinition['execute'] {
  return async (args: unknown, exec: ToolExecution) => {
    if (taskRequired) {
      throw new Error(`Tool "${rawName}" requires task-based execution, which this bridge does not support`)
    }
    // The agent loop passes `JSON.parse(model_arguments)` which is usually an
    // object, but can be any JSON value if the model misbehaves (outputs a bare
    // string/number/null). Fallback to {} lets the MCP server produce a
    // specific "missing required param" error the model can learn from.
    const argsObj = (typeof args === 'object' && args !== null ? args : {}) as Record<string, unknown>
    const result = await callToolUncached(client, rawName, argsObj, exec, opts)

    // The SDK may return a legacy `toolResult` shape; normalize to content array.
    if (!Array.isArray(result.content)) {
      const rendered: unknown = 'toolResult' in result
        ? JSON.stringify(result.toolResult)
        : '(no output)'
      const text = typeof rendered === 'string' ? rendered : '(no output)'
      if (result.isError === true) throw new Error(text)
      return {
        content: [{ type: 'text', text }],
        ...result.structuredContent !== undefined

View on GitHub (pinned to b150a551b8)

Solutions

1. Do not call tools that require task-based execution through this bridge.

When it happens

Trigger: Thrown at packages/mcp/mcp-client/src/tools.ts:313 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/8bbea8b919998409. Report an issue: GitHub.