Method validateToolOutput

src/server/mcp.ts:287–319

* Validates tool output against the tool's output schema.

(tool: RegisteredTool, result: CallToolResult | CreateTaskResult, toolName: string)

     * Validates tool output against the tool's output schema.
     */
    private async validateToolOutput(tool: RegisteredTool, result: CallToolResult | CreateTaskResult, toolName: string): Promise<void> {
        if (!tool.outputSchema) {
            return;
        }

        // Only validate CallToolResult, not CreateTaskResult
        if (!('content' in result)) {
            return;
        }

        if (result.isError) {
            return;
        }

        if (!result.structuredContent) {
            throw new McpError(
                ErrorCode.InvalidParams,
                `Output validation error: Tool ${toolName} has an output schema but no structured content was provided`
            );
        }

        // if the tool has an output schema, validate structured content
        const outputObj = normalizeObjectSchema(tool.outputSchema) as AnyObjectSchema;
        const parseResult = await safeParseAsync(outputObj, result.structuredContent);
        if (!parseResult.success) {
            const error = 'error' in parseResult ? parseResult.error : 'Unknown error';
            const errorMessage = getParseErrorMessage(error);
            throw new McpError(
                ErrorCode.InvalidParams,
                `Output validation error: Invalid structured content for tool ${toolName}: ${errorMessage}`
            );
        }
    }

    /**
     * Executes a tool handler (either regular or task-based).