deepseek-ai/deepseek-harness · error · Error

tool "${name}" parameters must be lossless JSON before schem

Error message

tool "${name}" parameters must be lossless JSON before schema projection

What it means

Error "tool "${name}" parameters must be lossless JSON before schema projection" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/tools/src/index.ts:1260

      .map((definition): ToolSdkSchema => {
        const output = snapshotJsonValue(definition.output.schema)
        /* v8 ignore next -- registration already validated and retained this schema as lossless JSON. */
        if (output === undefined) {
          throw new Error(`tool "${definition.name}" output schema must be lossless JSON before SDK projection`)
        }
        return {
          ...this.schemaOf(definition, true),
          output,
        }
      })
  }

  /** Project one definition onto the model-facing schema fields. */
  private schemaOf(definition: ToolDefinition, detachParameters: boolean): ToolSchema {
    const { name, description, parameters } = definition
    const detached = detachParameters ? snapshotJsonValue(parameters) : parameters
    if (detached === undefined) {
      throw new Error(`tool "${name}" parameters must be lossless JSON before schema projection`)
    }
    return {
      name,
      description,
      parameters: detached,
    }
  }

  /**
   * Classify a pending call through the caller's visible tool definition. Only
   * an exact `true` is parallel; unknown, hidden, undeclared, invalid, or
   * throwing classifiers are exclusive.
   * @param exec - call name, parsed arguments, and optional agent scope.
   * @returns the fail-closed scheduling mode.
   */
  executionMode(exec: ToolExecutionInput): ToolExecutionMode {
    const tool = this.resolveExecution(exec.name, exec.agent, exec.parent !== undefined)
    if (!tool?.isConcurrencySafe) return { kind: 'exclusive' }

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/tools/src/index.ts:1260 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/d4804ee1b36092c1. Report an issue: GitHub.